Interferometer, and optical assembly each having a three-pin mount for mounting an optical element at at least three points or areas and method of mounting same

ABSTRACT

A frame for optics used in interferometers that may include different materials having substantially similar, identical, or as close as practicable coefficients of thermal expansion from the material(s) used to make the beamsplitter and/or compensator without warping, bending, tilting or distorting the optics. The beamsplitter and/or compensator are mounted onto the frame of the interferometer using a three-point method of mounting, preferably using three pins for each component. Preferably, the pins are made of the same material as the beamsplitter and compensator, and all three components are made of Potassium Bromide (“KBr”) or Calcium Fluoride (“CaF 2 ”) such that the optic instrument can operate to scan into the mid or far infrared. Stability in optical alignment is therefore achieved without requiring the optic instrument include only one material. The invention provides stability in situations where it is not possible to utilize a single material for every component of the interferometer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/560,510, filed on Jul. 27, 2012, the entirety of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to the field of optical devices, and, moreparticularly, to interferometers, including monolithic interferometers,optical assemblies, and methods of mounting same. Such interferometersor interferometer optical assemblies provide stability in opticalalignment by, among other factors, using a single material. The presentinvention provides stability in situations where it is not possible toutilize a single material for every component of the interferometer oroptical assembly.

Fourier transform infrared (“FTIR”) spectrometers are well known in theart. Michelson interferometers function by splitting a beam ofelectromagnetic radiation into two separate beams via a beam splitter.Each beam travels along its own path, e.g., a reference path of fixedlength and a measurement path of variable length. A reflecting element,such as a retroreflector, is placed in the path of each beam and returnsthem both to the beam splitter. The beams are there recombined into asingle exit beam. The variable path length causes the combined exit beamto be amplitude modulated due to interference between the fixed andvariable length beams. By analyzing the output beam, the spectrum, whichis the intensity of the input beam as a function of frequency, may bederived after suitable calibration.

When the above interferometer is employed in a FTIR spectrometer, theexit beam is focused upon a detector. If a sample is placed such thatthe modulated beam passes through it prior to impinging upon thedetector, the analysis performed can determine the absorption spectrumof the sample. The sample may also be placed otherwise in thearrangement to obtain other characteristics.

Because Michelson interferometers rely upon the interference fromrecombination of the two beams, a quality factor of such a device is thedegree to which the optical elements remain aligned. The beam splitterand mirror-supporting structures must be isolated to the greatestpossible degree from extraneous forces which would tend to producedistortions of the structure. Such forces and resultant distortionsintroduce inaccuracies into the optical measurements. The forces mayarise from vibrational effects from the environment and can berotational or translational in nature. A similarly pervasive issueconcerns distortions due to changes in the thermal environment. Needlessto say, considerations of weight, size, facility of use, efficiency,manufacturing cost and feasibility are also of primary importance.

Prior art optical assemblies used in the construction of standardMichelson interferometers, and other type interferometers, haveconsisted primarily of structures having parts which are in need of highaccuracy alignment. For example, the arrangement of the two reflectingassemblies and the beamsplitter must be highly accurate in theperpendicular and reflecting arrangements in order to avoid errorsintroduced due to any such misalignment. The trouble with these priorart interferometers and optical assemblies arises from the costsinvolved in meticulously aligning the optical elements, the necessityfor active subsystems to maintain the alignment, and subsequent costs toservice and readjust the interferometer if shocks and vibrations haveintroduced uncompensated misalignment.

U.S. Pat. Nos. 5,949,543 and 6,141,101 to Bleier and Vishnia addressedthe above issues with a monolithic interferometer constructed from asingle material, preferably a material having a low coefficient ofthermal expansion. However, it is not always possible to utilize amonolithic interferometer made out of a single material becausematerials having reflectance/transmittance properties appropriate to anecessary wavelength of light may not technically or economically lendthemselves to elements of the monolithic interferometer other than theoptical elements. For example, certain materials do not possesssufficient mechanical properties to be used as support structures forthe interferometer, and certain materials can be expensive, requirefrequent cleaning and may be easily damaged.

Accordingly, it would be desirable to provide an interferometer and/oran interferometer optical assembly with optical elements of a differentmaterial than the remainder of the interferometer or interferometeroptical assembly that, nevertheless, provides high accuracymeasurements. Such an interferometer or interferometer optical assemblywould facilitate easy and cost effective maintenance by replacement ofthe entire optical assembly, which optical assembly is not subject tomisalignment from shocks, vibrations, or temperature changes due to themonolithic structure of the assembly. It would be further desirable toprovide an optical assembly which allows for use of multiple wavelengthlight sources to achieve a “fringe” result in a spectrometryapplication.

It would also be desirable to provide a method of mounting aninterferometer and/or an interferometer optical assembly to achieve thedesired results.

SUMMARY OF THE INVENTION

In accordance with the invention, an improved interferometer, aninterferometer optical assembly and method of mounting same areprovided. Accordingly, it is a broad object of the invention to providean interferometer or interferometer optical assembly for use with aprecision instrument comprising at least a frame having a first plateand a second plate and a beamsplitter having a first surface and asecond surface, the beamsplitter being made of a first materialextending between the first plate and the second plate of the frame.Preferably, the one or more components of the frame are all formed ofone of the same second material or materials that is/are different fromthe first material, but having substantially the same or the samecoefficient of thermal expansion as that of the first material, orhaving a coefficient of thermal expansion that is as close aspracticable thereto, such that the beamsplitter has limited or noexposure to at least one of bending, warping, tilting and distorting.The beamsplitter is preferably located inside the frame in an interiorspace thereof.

The three-point or three-pin arrangement of the present invention may beused to mount (e.g., kinematically, semi-kinematically, etc.) any typeof optic, such as, but not limited to, a mirror, a beamsplitter, acompensator, other types of reflectors, a refractor, etc., into any typeof instrument, such as, but not limited to, an interferometer, aninterferometer optical assembly, a frame, any other optical device orprecision optical device, etc. Using the three-pin arrangement of thepresent invention provides several advantages, including, but notlimited to, permitting the use of interchangeable parts (e.g., pin(s))for each point of contact, providing better adjustability in assembly,saving time and money by not requiring precision machining on the optic,etc. For example, the beamsplitter may be attached to the frame by asecuring apparatus having three pins that operate to kinematically mountthe beamsplitter to the frame using a three-pin or three-pointarrangement. The beamsplitter securing apparatus may be used with one ormore embodiments of the interferometer or the interferometer opticalassembly having the first and second materials as aforementioned, or,alternatively, may be used with one or more other embodiments of theinterferometer or the interferometer optical assembly comprising anymaterial (and not being limited to the first and the second materials asaforementioned). The three pins each have a first end and a second end,and preferably include a bonding material or shell on the peripherythereof. When using the beamsplitter securing apparatus, thebeamsplitter preferably includes at least one landing area or surface(which may be coplanar) on a third surface thereof and at least twolanding areas or surfaces (which may be coplanar) on a fourth surfacethereof, the third and fourth surfaces extending between the first andsecond surfaces of the beamsplitter. Corresponding holes may be locatedon the first and second plates such that the corresponding holes operateto receive at least one pin therein while the pins are disposed on oragainst their respective landing areas or surfaces to form one or moreattachments between the beamsplitter and the first and second plates ofthe frame. The third surface of the beamsplitter operates to be disposedsubstantially against or adjacent to the first plate of the frame, andthe fourth surface of the beamsplitter operates to be disposedsubstantially against or adjacent to the second plate of the frame.

A mirror or mirrors may be attached to the frame, the mirror(s) having areflecting surface in a reflecting relation with the beamsplitter.

The interferometer or interferometer optical assembly may furthercomprise a compensator extending between the first plate and the secondplate of the frame. The compensator may be disposed between the mirrorand the beamsplitter, and the compensator may have its own compensatorsecuring apparatus having three pins that operate to kinematically mountthe compensator to the frame using a three-pin or three-pointarrangement. The compensator securing apparatus may be used with one ormore embodiments of the interferometer or the interferometer opticalassembly having the first and second materials as aforementioned, or,alternatively, may be used with one or more other embodiments of theinterferometer or the interferometer optical assembly comprising anymaterial (and not being limited to the first and the second materials asaforementioned). The three pins each have a first end and a second end,and preferably include a bonding material or shell on the peripherythereof. When using the compensator securing apparatus, the compensatorpreferably includes at least one landing area or surface (which may becoplanar) on a third surface thereof and at least two landing areas orsurfaces (which may be coplanar) on a fourth surface thereof, the thirdand fourth surfaces extending between the first and second surfaces ofthe compensator. Corresponding holes may be located on the first andsecond plates such that the corresponding holes operate to receive atleast one pin therein while the pins are disposed on or against theirrespective landing areas or surfaces to form one or more attachmentsbetween the compensator and the first and second plates of the frame.The third surface of the compensator operates to be disposedsubstantially against or adjacent to the first plate of the frame, andthe fourth surface of the compensator operates to be disposedsubstantially against or adjacent to the second plate of the frame.

The optical assembly may also have a second mirror or mirrors attachedto the frame having a reflecting surface facing away from the frameinterior space (e.g., for use with a retroreflector located outside ofthe frame), or otherwise forming a part of the second mentionedmeasurement path of variable optical path length of the interferometer.

The optical assembly may also have a protruding member to further reduceand/or eliminate one or more stresses, including stresses resulting fromtemperature change, therefrom.

In an alternative embodiment of the present invention, an interferometeris disclosed comprising a radiation source; a beamsplitter having afirst surface and a second surface, the beamsplitter comprising at leastone first material; a frame comprising a first plate and a second platehaving the beamsplitter extending therebetween; a retroreflectordisposed externally to the frame, the retroreflector operating to moverelative to the frame; a first mirror attached to the frame and having areflecting surface in a first direct reflecting relation with thebeamsplitter; and a second mirror attached to the frame and having areflecting surface in a second direct reflecting relation with theretroreflector, wherein: (i) the retroreflector has a retroreflectionrelation with both the beamsplitter and the second mirror; (ii) theframe comprises at least a second material that is different from the atleast one first material; and (iii) the at least one first material hasa coefficient of thermal expansion that is identical to or substantiallysimilar to a coefficient of thermal expansion of the at least secondmaterial, or has a coefficient of thermal expansion that is as close aspracticable thereto, such that the beamsplitter has limited or noexposure to at least one of bending, warping, tilting and distorting.The interferometer may incorporate one or more features as discussedherein of the interferometer optical assembly of the present invention.For example, the retroreflector may be external to an interior space ofthe frame, moveable relative to the frame and has a retroreflectionrelation with both the beamsplitter and the second mirror. Thebeamsplitter may be attached to the frame by a beamsplitter securingapparatus having at least three pins that operate to kinematically mountthe beamsplitter via a three-pin or three-point arrangement asaforementioned. A compensator and/or compensator securing apparatus maybe employed with the interferometer in one or more embodiments. Thedescribed interferometer may have the same optional components,structure, etc. as the interferometer optical assembly described herein.

The method of mounting the one or more components of the interferometerand/or interferometer optical assembly comprises at least disposing abeamsplitter having a first surface and a second surface in between afirst plate and a second plate of a frame such that the beamsplitterextends between the first plate and the second plate, the beamsplittercomprising at least one first material, wherein (i) the frame comprisesat least a second material that is different from the at least one firstmaterial; and (ii) the at least one first material has a coefficient ofthermal expansion that is identical to or substantially similar to acoefficient of thermal expansion of the at least second material, or hasa coefficient of thermal expansion that is as close as practicablethereto, such that the beamsplitter has limited or no exposure to atleast one of bending, warping, tilting and distorting. The method mayinclude disposing, mounting, connecting, etc. one or more othercomponents of the interferometer and/or interferometer optical assemblyas described herein, including, but not limited to, a compensator suchthat it the compensator extends between the first plate and the secondplate of the frame; a protruding member on the frame such that itextends from a surface of the optical structure, wherein the protrudingmember is either integrally formed with, or bonded/fused to, the surfaceof the frame of the optical structure, one or more support members onthe frame; etc. The beamsplitter and/or the compensator may be mountedto the frame by using a respective securing apparatus each having threepins that operate to kinematically mount the beamsplitter and/or thecompensator using a three-pin or three-point arrangement. The describedmethod may incorporate forming, providing, disposing, etc. the sameoptional components, structure, etc. as the interferometer opticalassembly and/or interferometer described herein.

Accordingly, it is an object of the invention to provide an improvedinterferometer, optical assembly and method of mounting same.

Another object of the invention is to provide an improved interferometerand/or optical assembly for an optical structure which causes minimalexternal stresses to, and reduces and/or eliminates tilting, bending,warping, distorting, etc. of, the reflective and refractive surfaces,such as the beamsplitter, compensator and mirror(s) of theinterferometer and/or interferometer optical assembly.

A further object of the invention is to provide an improvedinterferometer and/or optical assembly that causes minimal externalstresses to, and reduces and/or eliminates tilting, bending, warping,distorting, etc. of one or more components thereof by using at least twodifferent materials for the one or more components, where the twodifferent materials have the same or substantially the same coefficientof thermal expansion, or coefficients of thermal expansion that are asclose as practicable to each other.

Yet a further object of the invention is to provide an improvedinterferometer and/or optical assembly wherein the mounting of thecomponents of the interferometer is easy and results in a secure,structural design of the interferometer and/or interferometer opticalassembly.

It is even a further object of the invention to provide a method ofmounting one or more components of an interferometer and/or opticalassembly.

Other objects of the invention will in part be obvious and will in partbe apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purposes of illustrating the various aspects of the invention,wherein like numerals indicate like elements, there are shown in thedrawings simplified forms that may be employed, it being understood,however, that the invention is not limited by or to the precisearrangements and instrumentalities shown. To assist those of ordinaryskill in the relevant art in making and using the subject matter hereof,reference is made to the appended drawings and figures, wherein:

FIG. 1 is a diagram showing how radiation is reflected in a prior artMichelson interferometer;

FIG. 2 is a perspective view of an interferometer having the monolithicoptical assembly of the invention;

FIG. 3 is a perspective view of a monolithic optical assembly of theprior art;

FIG. 4 is a top view of a monolithic optical assembly of the prior art;

FIG. 5 is a perspective view of at least one embodiment of aninterferometer in accordance with one or more aspects of the presentinvention;

FIG. 6 is a diagram view of the optics of at least one embodiment of aninterferometer in accordance with one or more aspects of the presentinvention;

FIG. 7A is an exploded perspective view of FIG. 6 in accordance with oneor more aspects of the present invention;

FIG. 7B is a diagram view of the landing areas or surfaces of one ormore components, and of the pins and holes of the plates of at least oneembodiment of an interferometer in accordance with one or more aspectsof the present invention;

FIGS. 8-9 are perspective bottom views of the interferometer embodimentshown in FIG. 6 in accordance with one or more aspects of the presentinvention;

FIGS. 10-11 are perspective top views of the interferometer embodimentshown in FIG. 6 in accordance with one or more aspects of the presentinvention;

FIGS. 12-13 are perspective side views of the interferometer embodimentshown in FIG. 6 in accordance with one or more aspects of the presentinvention;

FIG. 14 is a perspective view of an alternative embodiment of aninterferometer in accordance with one or more aspects of the presentinvention; and

FIGS. 15A-15F are cross-sectional views taken along the diameter ofvarious embodiments of the protruding member employing differentgeometrical shapes for the groove/relieved portion thereof in accordancewith one or more embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An improved interferometer, optical assembly, and method of mountingsame, are disclosed herein. The interferometer and/or optical assemblymay include a beamsplitter and/or a compensator made from at least afirst material and a frame having at least a first plate and a secondplate made of at least a second material. Preferably, the first andsecond materials have identical or substantially the same coefficientsof thermal expansion, or have coefficients of thermal expansion that areas close as practicable to each other, such that one or more componentsof the interferometer and/or optical assembly, including, but notlimited to, the beamsplitter, the compensator, etc., have limited or noexposure to at least one of bending, warping, tilting and distorting.Preferably, one or more components of the interferometer and/or theoptical assembly, such as, but not limited to, the beamsplitter, thecompensator, etc., are kinematically connected to the frame using anapparatus having three pins each having a first end and a second end.The improved interferometer may have the grooved/relieved protrudingmember extending from a surface of the first plate or the second platethereof, the protruding member operating to connect to a mount formounting the interferometer to another structure and to dissipate and/oreliminate one or more stresses passing through the protruding member,thereby preventing the one or more stresses from affecting the opticalassembly and/or the interferometer.

Turning now to the details of the figures, FIG. 1 shows the generalprincipals of a standard Michelson interferometer. The Michelsoninterferometer has a radiation source 10 which sends a radiation beam 20towards beamsplitter 30 which is situated at an angle to two mirrors, afixed mirror 40 and a movable mirror 50. Radiation beam 20 is partiallyreflected toward fixed mirror 40 in the form of radiation beam 22, andis partially transmitted through beamsplitter 30 towards movable mirror50 as radiation beam 24. Beam 22 is then reflected off of fixed mirror40, back towards beamsplitter 30, where it is once again partiallysplit, sending some radiation 25 back towards source 10, and someradiation 26 toward detector 60. Similarly, beam 24 reflects off ofmovable mirror 50 and is reflected back toward beamsplitter 30. Herealso, beam 24 is again split, sending some radiation back to source 10and other radiation 26 toward detector 60.

Detector 60 measures the interference between the two radiation beamsemanating from the single radiation source. These beams have, by design,traveled different distances (optical path lengths), which creates afringe effect which is measurable by detector 60.

FIG. 2 shows the lay out and component structure of a Michelsoninterferometer of the prior art, e.g., U.S. Pat. No. 6,141,101 toBleier, herein incorporated by reference. FIG. 2 shows interferometer100, and includes a radiation source 110, a beamsplitter 130, a movablereflecting assembly 150, a fixed reflecting assembly 140 and a detector142. Radiation source 110 is mounted in a secure position by mountingassembly 112. With radiation source 110 in mounting assembly 112,radiation beam 120 is alignable along a path which will fix thedirection of the beam at the appropriate angle to beamsplitter 130.

Radiation source 110 can be collimated white light for generalinterferometry applications, such as optical surface profiling,collimated infrared light for an infrared spectrometer, a singlecollimated radiation intensity laser light source, etc., for accuratedistance measurements or any now known, or which become known in thefuture, light/radiation source used in spectroscopy, measurement, orother use. Additionally or alternatively, radiation source 110 may be abroadband light source (i.e., a light source that radiates on abroadband wavelength; also referred to herein as (and usedinterchangeably with) “light”, “light source”, “radiation”, “lightsource/beam”, “radiation source”, “radiation beam”, “radiation/lightsource”, “white light source”, and “radiation/light beam”).

Movable reflecting assembly 150 may utilize a hollow corner-cuberetroreflector 152. The hollow corner-cube retroreflector 152 could bemade in accordance with the disclosure of U.S. Pat. No. 3,663,084 toLipkins, herein incorporated by reference.

Retroreflector 152 is mounted to a movable base assembly 144, whichassembly allows for adjustment of the location of retroreflector 152 ina line along the path of beam 120. The displacement of assembly 144 isadjustable; e.g., through use of adjusting knob 146. Other means ofmoving assembly 144 are also anticipated by the invention, includingsuch means that might allow for continuous, uniform movement of assembly144. For example, means of movement of assembly 144 might beaccomplished in accordance with the structure described in U.S. Pat. No.5,335,111 to Bleier, herein incorporated by reference, or by U.S. patentapplication Ser. No. 12/505,279 filed on Jul. 17, 2009 and which issuedas U.S. Pat. No. 8,205,852 on Jun. 26, 2012.

The use of retroreflector 152 as the movable reflecting assembly 150allows for any angular orientation of retroreflector 152, preferably aslong as edge portions of the retroreflector mirrors do not clip aportion of beam 120. Importantly, even if one or more portions of theretroreflector mirror(s) do clip a portion of beam 120, theinterferometer still works.

From the foregoing, the length of the beam paths 20, 22 and 26 are fixedand known while the length of beam path 24 may be varied. The variationof the length of beam path 24 is, of course, critical to the operationof the interferometer, as is knowing the length as precisely aspossible.

A monolithic optical assembly 200, as seen in FIGS. 3-4, comprises abeamsplitter 130 and reflecting assembly 140 mounted within a top plate260, a bottom plate 270 and at least first and second support members210 and 220, respectively. As an add-on for some additional structuralstability, which stability is not essential, third support member 230can also be used. Support member 210 has an edge 214. A portion of edge214 is bonded to a portion of edge 262 of top plate 260, while anotherportion of edge 214 of support member 210 is bonded to a portion of anedge surface of bottom plate 270.

As shown in FIG. 4, around the corner from support member 210, is secondsupport member 220. Second support member 220 is bonded to top andbottom plates 260 and 270 along different portions of a surface 222thereof. The portions of surface 222 of support member 220 are bonded toportions of an edge surface 264 of top plate 260 and edge surface 274 ofbottom plate 270.

Beamsplitter 130 may be comprised of two panels bonded to each otheralong a common surface. The common surface is an optically flatreflecting surface having a beamsplitter coating thereon. Beamsplitter130 is bonded along portions of top edges 137 to portions of bottomsurface 267 of top plate 260, and along portions of bottom edges 138 toportions of top surface 278 of bottom plate 270. One panel ofbeamsplitter 130 is a compensating member. The purpose of thecompensating panel is to equate the material portions of the opticalpath difference of the two beams created by the beamsplitter. Withoutthe compensating panel, the beam transmitted through the beamsplitterwould travel through the optical material of the beamsplitter twice,while the reflected beam would travel through optical material zerotimes. By adding a compensating panel, ideally of the same thickness,wedge, and material as the beamsplitter, both beams travel twice throughequal portions of optical material before being recombined at thebeamsplitter surface, thereby equating any differences they may haveexperienced in that portion of their optical path length throughmaterial. The invention also anticipates a structure where thecompensating panel is separated from the beamsplitter.

The support combination of first support member 210, second supportmember 220 and beamsplitter 130 between top plate 260 and bottom plate270 creates a monolithic structure. As earlier discussed, it is alsopossible to have third support member 230 situated between portions ofthird edge surfaces 266 and 276 of top and bottom plates 260 and 270,respectively, as seen in the figures.

To complete the required reflecting elements of a Michelsoninterferometer, it is seen in the figures that a mirror panel 140 isbonded to a portion of top surface 278 of bottom plate 270, and to asecond edge surface 214 of support member 210. Mirror panel 140 isslightly over hanging top surface 278 of bottom plate 270 by a portionof a bottom edge surface of mirror panel 140, and is bonded betweenthese touching surfaces. Bonding also takes effect between the side edgesurface of mirror panel 140 that touches edge surface 214 of supportmember 210. Bonding must avoid distorting the optically flat nature ofthe reflecting surface 142 of mirror panel 140.

Since mirror panel 140 is fixedly attached to assembly 200, as has justbeen discussed, there is no necessity for panel 140 to be other than asingle, flat paneled mirror; for example, panel 140 does not need to bea retroreflector. One of the benefits of using a retroreflector (as hasbeen discussed earlier regarding movable reflecting assembly 150 and asdiscussed further below) in a structure is that the orientation of theretroreflector is unimportant. The secured mounting of panel 140 to themonolithic structure assures that the orientation of panel 140 will notfluctuate due to vibration and shock, and therefore, a retroreflector isunnecessary (although a retroreflector alternatively could of course beutilized).

The portion of beam 120 that passes through beam splitter 130 andinteracts with retroreflector 152 may also be returned via a secondmirror panel, similar to mirror panel 140. This second mirror panel maybe made integral with second support member 220 or be a separate panelsupported by one or all of the second support member 220, edge 264 oftop plate 260 and bottom plate 270.

Assembly 200 can also have a fourth support member 240. While the mainpurpose of fourth support member 240 is not to help stabilize themonolithic structure of assembly 200, it is nevertheless called asupport member herein. Instead, fourth support member 240 is positionedin relation to the path traveled by beam 120 so as to allow beam 120 topass through opening 242 in member 240, to travel between beamsplitter130 and movable reflecting assembly 150. One or both of elements 244,246 can comprise reflecting elements for returning beam 120 toretroreflector 252.

All members 210, 220, 230, 240, 260, 270, 130 and 140, of assembly 200,may be made of the same material. The material preferably being fusedquartz or annealed Pyrex (e.g., any type of annealed borosilicate glassand/or glasses having a low coefficient of thermal expansion). The useof identical materials allows the coefficients of expansion of thematerials to be identical, so that any temperature changes experiencedby assembly 200 is experienced equally throughout each member to allowassembly 200 to expand and contract uniformly, thereby substantiallyremoving distortions in the reflecting surfaces of beamsplitter 130 andmirror panel 140.

The monolithic construction discussed above has the benefit of highthermal stability in its optical alignment. This stability derives fromthe construction of the unit from a single, low expansion material suchas Pyrex glass (e.g., any type of annealed borosilicate glass and/orglasses having a low coefficient of thermal expansion), fused silica,Zerodur or Cervit. However, in the application of infrared Fouriertransform spectroscopy, often called FTIR, it may not be possible tofabricate the beamsplitter and compensating plate from the same materialas the assembly. This may occur when the need for high transmission inthe infrared (“IR”) is not consistent with available low expansionstructural materials. In particular, the high IR transmission opticalmaterial may have a much higher thermal expansion coefficient.

Attaching optical elements having a thermal expansion coefficientdifferent from the expansion coefficient of the remainder of theassembly could introduce wavefront distortion in the interfering opticalbeams or even result in mechanical failure under temperature changes. Inorder to take advantage of the permanent optical alignment afforded by amonolithic assembly, the connection between optical elements, e.g.,beamsplitter and compensating plate, and the rest of the monolithicassembly should transmit minimal stress from this assembly to theoptical elements under temperature changes.

In accordance with at least one aspect of the present invention, FIG. 5shows at least one embodiment of an improved monolithic interferometeroptical assembly 200 having at least a frame 9, a beamsplitter 11, amirror 4, and a mirror 5. Alternatively, the mirrors 4, 5 may be removedor not installed in the interferometer optical assembly 200 yet forshipping, transportation, etc. The interferometer optical assembly 200may further include one or more of the following components: acompensator 8, a first support member 3 a, a second support member 3 b,and a protruding member 90. Preferably, one or more components of theinterferometer optical assembly 200 are made of at least two differentmaterials having identical, substantially the same, or as close aspracticable coefficients of thermal expansion (“CTE”) such that the oneor more components of the interferometer optical assembly 200, wheninteracting in one or more different thermal environments, have limitedor no exposure to at least one of bending, warping, tilting anddistorting. Preferably, the beamsplitter 11 and/or the compensator 8 arekinematically connected to the first plate 1 and the second plate 2 ofthe frame 9 of the interferometer optical assembly 200 using a three pin12 a mounting arrangement where the pins 12 a are disposed in respectiveholes 12 b in the first plate 1 and/or the second plate 2 of theinterferometer optical assembly 200, and the pins 12 a are adjacent to,and abut (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.), one or more coplanar landingareas 56 (discussed further below) of the beamsplitter 11 and/or thecompensator 8 of the interferometer optical assembly 200.

As shown in the diagram of FIG. 6 (showing only the beams and theoptical elements of at least one embodiment of the present invention),in a two-beam interferometer, two beams are created from a singleincident ray 13 striking the beamsplitter 11. The two beams are areflected beam 14 and a transmitted beam 15. The reflected beam 14 isreflected by the beamsplitter 11 towards the mirror 5. The reflectedbeam 14 passes through the compensator plate 8 on the way to the mirror5 and while returning to the beamsplitter 11. In a well-alignedinterferometer, the reflected beam 14 is exactly perpendicular to thefixed mirror 5. The transmitted beam 15, after exiting the beamsplitter11, proceeds to the retroreflector 152 which reflects a beam 16 backtoward a reflecting surface 17 disposed on the mirror 4 (furtherdiscussed below). In a well-aligned interferometer, the beam 15 isexactly parallel to the beam 16, which is perpendicular to thereflecting surface 17 of the mirror 4. It is an aim that, once alignmentof the interferometer optical assembly 200 is achieved during assembly,final assembly may permanently and rigidly lock this alignment into thestructure thereof.

The beamsplitter 11 and/or the compensator 8 must be of materialtransmissive to the light, often IR light, being processed by theinterferometer 100 and/or the interferometer optical assembly 200.Preferably, the beamsplitter 11 and/or the compensator 8 are wedged toprevent interference effects from the front and back surfaces fromcreating ghost beams that can interfere with the main beams, such asbeams 13, 14, 15, 16, in the application. Preferably, the compensator 8is made of the same material as the beamsplitter 11 with substantiallyand ideally the same thickness and wedge angle to compensate the opticalpath 13-14 with the optical path 15-16, unless a purposefulmiscompensation is desired. Even in such a case where a purposefulmiscompensation is desired, the requirement to thermally match (orobtain as close a match as possible while obtaining the desired result)all components of assembly 200, as closely as practicable, stillobtains. In one or more embodiments, any means of improved mounting ofthe beamsplitter 11 should be repeated for the compensator 8 forachieving the desired results. Typically, the beamsplitter 11 and/or thecompensator 8 may be made from Zinc Selenide (referred to as “ZnSe”).

Making the beamsplitter 11 and/or the compensator 8 from PotassiumBromide (“KBr”) as opposed to ZnSe enables the interferometer opticalassembly 200 to be useful to about 30 microns, whereas the ZnSeinterferometer typically operates only to about 16 microns. As such,preferably, the beamsplitter 11 and the compensator 8 are made from KBrin accordance with at least one aspect of the present invention. Adifficulty in making these components from KBr (which has a coefficientof thermal expansion (“CTE”) of about 40 ppm/degree C.), however, is toavoid unnecessary stresses, including those resulting from temperaturechanges, when interacting with other components of the assembly 200. Asexplained above, other components of an interferometer (e.g.,interferometer 100), such as one or more components of interferometeroptical assembly 200, may be made from fused quartz or fine annealedPyrex (i.e., any type of borosilicate glass or glasses having a lowcoefficient of thermal expansion). Again, wisdom in the art dictates orsuggests that such components be made from a low expansion material(i.e., a material have a low CTE), such as, but not limited to, fusedquartz or fine annealed Pyrex (which have a CTE of about 3 ppm/degreeC.), to avoid thermal instability and provide high thermal stability inthe optical alignment of the assembly 200. Additionally, salt windows,such as the beamsplitter 11 or the compensator 8 when made from KBr,from Calcium Fluoride (“CaF₂”) (further discussed below), from a highCTE material (i.e., a material having a CTE of at least one of: about 5ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degree C.-30ppm/degree C., and greater than 30 ppm/degree C.) or other fragile,thermally troublesome material(s), can be expensive, require frequentcleaning, are relatively fragile and can be easily damaged. As such, oneskilled in the art would be deterred from making such components out ofKBr, CaF₂ or other material having a high CTE due to its fragility andhigh CTE. However, to achieve the higher scanning range to about 30microns for KBr as aforementioned, it is important to proceed contraryto accepted wisdom in the field of optics and interferometer assemblydesign by using a first material, such as KBr, for the beamsplitter 11and the compensator 8 of the interferometer assembly 200.

Additionally or alternatively, the first material used to make thebeamsplitter 11 and/or the compensator 8 may be Calcium Fluoride(“CaF₂”) as aforementioned. As another option for such an opticalapplication, CaF₂ has a CTE of 18.9 ppm/degree C. Since CaF₂ is also asalt, one skilled in the art would be deterred from making such opticalcomponents out of CaF₂ as aforementioned due to the fragility andthermally troublesome nature thereof. CaF₂ is useful when operating onlyto about 7 μm. Otherwise, however, it is much more durable than KBr, andprovides an alternative to ZnSe in certain situations. As such, it isagain important to proceed contrary to the aforementioned acceptedwisdom by using a first material, such as CaF₂, for the beamsplitter 11and the compensator 8 of the interferometer assembly 200. Additionallyor alternatively, the first material may be a material having a CTE ofat least one of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C.

Thus, to compensate for the CTE difference and to provide the desiredmechanical properties, it, surprisingly, is important to select asecond, different material when making the frame 9 of the assembly 200.Preferably, the second material has the same CTE, substantially the sameCTE, or a CTE that is as close as practicable (e.g., in the case of KBr,in the case of CaF₂, and/or in the case of a material having a CTE of atleast one of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C. asdiscussed above, a CTE of a second material is “as close as practicable”to the CTE of KBr, CaF₂, and/or the material having a CTE of at leastone of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C. whenthe CTE of the second material is at least one of: about 23 ppm/degreeCelsius, higher than 23 ppm/degree Celsius, about 23.4 to about 23.6ppm/degree Celsius, about 23 to about 27 ppm/degree Celsius, about 23 toabout 28 ppm/degree Celsius, etc.) as that of the first material, e.g.,KBr, CaF₂, and a material having a CTE of at least one of: about 5ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degree C.-30ppm/degree C., and greater than 30 ppm/degree C., etc. Given that thesecond materials each have a CTE that is higher than the traditionalmaterials of Pyrex or Quartz and that is as close as practicable to theCTE of the first material, the second materials of the present inventionrepresent a substantial improvement over those traditional materials(such as, but not limited to, glass) for building one or morecomponents, such as, but not limited to, the frame 9, the supportmembers/elements 3 a, 3 b, etc., of an interferometer or of theinterferometer optical assembly 200. It has been found that sufficientsecond materials, which have a CTE sufficiently close, or “as close aspracticable” to, the CTE of the first material, e.g., KBr, CaF₂, amaterial having a CTE of at least one of: about 5 ppm/degree C.-about 10ppm/degree C., about 10 ppm/degree C.-30 ppm/degree C., and greater than30 ppm/degree C., etc., may include at least one of: Zinc, Aluminum,Magnesium, an Aluminum-Zinc or a Zinc-Aluminum alloy.

The frame 9 of the assembly 200 includes at least a first plate 1 and asecond plate 2. Preferably, the first plate 1 and the second plate 2 aremade from the same material (e.g., the aforementioned second material).When one or more components of the frame 9 are made from a differentmaterial than the material used to make the beamsplitter 11 and/or thecompensator 8, preferably, the material used to make the one or morecomponents of the frame 9 and the material used to make the beamsplitter11 and/or the compensator 8 have identical, substantially the same, orsufficiently close (i.e., as closely as practicable) coefficients ofthermal expansion such that the one or more components have limited orno exposure to at least one of bending, warping, tilting and distorting.As such, preferably, the one or more components of the frame 9 are madefrom one of the second materials listed above, i.e., at least one of:Zinc, Aluminum, Magnesium, an Aluminum-Zinc or a Zinc-Aluminum alloy.The frame 9 may further include at least one of the first support member3 a and the second support member 3 b. Preferably, in at least oneembodiment (best seen in FIGS. 5 and 7-13), the frame 9 may be formedintegrally with one or more of the first support member 3 a and thesecond support member 3 b such that the first plate 1 and the secondplate 2 are integral (e.g., by way of the first support member 3 a, byway of the second support member 3 b, etc.). Additionally, there may bea plurality of first support members 3 a as shown in FIGS. 9 and 12-13in one embodiment and as shown in FIG. 14 in an alternative embodiment.In at least another embodiment (best seen in FIG. 14), the frame 9 maybe made of separate components such that the first plate 1′ and thesecond plate 2′ are not formed integrally (plate 1′ may be substantiallythe same, and have substantially the same properties/structureincorporated therein, as the plate 1 and plate 2′ may be substantiallythe same, and have substantially the same properties/structureincorporated therein, as the plate 2 as described above, with theexception that plate 1′ is not integrally formed with at least one ofplate 2′, the first support member 3 a, the second support member 3 b,etc.), and are connected or mounted to one or more separate components,e.g., the first support member 3 a, the second support member 3 b, etc.For example, the one or more components (e.g., the first support member3 a, the second support member 3 b, etc.) may be bonded or fused withthe first plate 1 and/or the second plate 2.

The pins 12 a each have first and second ends thereof, correspond torespective pin holes 12 b and operate to kinematically connect, ormount, one or more components, such as, but not limited to, the mirror5, the mirror 4, the beamsplitter 11, the compensator 8, etc., to theframe 9 of the interferometer optical assembly 200. Surprisingly, usingthe pins 12 a in a three-point or three-pin arrangement (as opposed tosome other means of connecting or mounting) to connect, or mount, theone or more components, and particular the optical components (e.g., thebeamsplitter 11, the compensator 8, the mirror 5, the reflecting surface17 of the mirror 4 and/or the mirror 4, etc.), kinematically orsemi-kinematically to the frame 9 of the interferometer optical assembly200: (i) focuses/enables only radial pressure on the pins 12 a,including at temperature change(s), without compromising the tiltposition of the optical elements/components of the interferometeroptical assembly 200 or interferometer 100; and (ii) overcomes/avoidspotential damage because of the one or more stresses, includingstress(es) from temperature change(s), especially when the pins 12 a areaccurately positioned, disposed, sitting, etc. in their respective holes12 b. The three-point or three-pin arrangement may be used to mount(e.g., kinematically, semi-kinematically, etc.) any type of optic, suchas, but not limited to, a mirror (e.g., the mirrors 4, 5), abeamsplitter (e.g., the beamsplitter 11), a compensator (e.g., thecompensator 8), other types of reflectors, a refractor, etc., into anytype of instrument, such as, but not limited to, an interferometer(e.g., the interferometer 100), an interferometer optical assembly(e.g., the optical assembly 200), a frame (e.g., the frame 9), any otheroptical device or precision optical device, etc. Using the three-pinarrangement of the present invention provides several advantages,including, but not limited to, permitting the use of interchangeableparts (e.g., pin(s) 12 a), providing better adjustability in assembly,saving time and money by not requiring precision machining on the optic,etc. Additionally, surprisingly, using the three-pin arrangementprovides unique structural integrity to the invention, especially whenthe invention includes materials having high or different CTE values orwhere there is a large unavoidable CTE mismatch (e.g., as is the casebetween KBr and a metal). This is even more valid in the one or moreembodiments where the pin(s) 12 a are made of the same material as theoptic being held or mounted. Preferably, the pin(s) 12 a are made fromthe same material as their respective optical components that thecorresponding pin(s) 12 a fix to the frame 9. For example, if thebeamsplitter 11 and the compensator 8 are made of the first material,e.g., KBr, CaF₂, a material having a CTE of at least one of: about 5ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degree C.-30ppm/degree C., and greater than 30 ppm/degree C., etc., then the pins 12a attached to the beamsplitter 11 and the compensator 8 may bepreferably made of the first material, such as, but not limited to, KBr,CaF₂, a material having a CTE of at least one of: about 5 ppm/degreeC.-about 10 ppm/degree C., about 10 ppm/degree C.-30 ppm/degree C., andgreater than 30 ppm/degree C., etc. As an additional example, if themirrors 4, 5 and/or the frame 9 are made of a metal alloy, then the pins12 a used to attach the mirrors 4, 5 to the frame 9 may be preferablymade of the same metal alloy. Thus, one or more of the pins 12 a asshown in the figures may be made of the same material or differentmaterial(s) from each other in one or more embodiments depending on thematerials used to make their respective components of the interferometeroptical assembly 200 or the interferometer 100.

As best seen in the exploded view of FIG. 7A, preferably, the pin(s) 12a may be coated or encapsulated in a bonding material or shell 13 (e.g.,on the periphery of the pin(s) 12 a, as a coating over the entire pin(s)12 a, etc.) such that the bonding material or shell 13 operates to bondthe pin(s) 12 a, especially when made of KBr, to the respective hole(s)12 b and/or landing areas 56 (discussed further below). The bondingmaterial or shell 13 further operates to dissipate the one or morestresses, which may try to affect the pin(s) 12 a. Alternatively oradditionally to bonding via a bonding material or shell 13, the pin(s)12 a may connect to the respective hole(s) 12 b via friction fitting orfusing (or adhering) and/or the pin(s) 12 a may connect to the landingareas 56 via fusing (or adhering) or adhesive action.

Unexpectedly, when the pin(s) 12 a are made of the first material, suchas, but not limited to, KBr, CaF₂, and a material having a CTE of atleast one of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C., etc.,and include a bonding material on at least a periphery thereof, thepin(s) 12 a: (i) are minimally affected or not affected by one or moreexternal stresses thereon, including stress(es) resulting fromtemperature change(s); and (ii) maintain their structural integrity tohold the one or more components, such as, but not limited to, themirrors 4 and 5, the beamsplitter 11, the compensator 8, etc., to theframe 9 of the interferometer optical assembly 200.

Additionally, using pin(s) 12 a, rather than some other means ofmounting/connecting, especially in a three-point or three-pinarrangement, proceeds contrary to wisdom in the optical assembly andinterferometer art because, while one skilled in the art would normallybe deterred from using pin(s) 12 a due to possible structural change(s)brought on by stress and/or temperature fluctuations, the three-point orthree-pin arrangement achieves a synergy where the pin(s) 12 a are notsubject to change by stress, such as temperature-induced stress. This isespecially true where the pin(s) 12 a are made of the same material,such as KBr, CaF₂, and a material having a CTE of at least one of: about5 ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degree C.-30ppm/degree C., and greater than 30 ppm/degree C., etc., so that, evenwhen the pin(s) 12 a become longer or shorter due to temperature change,the pin(s) 12 a maintain the structural integrity of the opticalassembly 200. This is further the case when the pin(s) 12 a, e.g., madeof the first material, such as, KBr, CaF₂, and a material having a CTEof at least one of: about 5 ppm/degree C.-about 10 ppm/degree C., about10 ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C.,etc., are encapsulated/covered, in part or in whole, by the bondingmaterial or shell 13. Preferably, the pin(s) 12 a are not polished whenmade of KBr, CaF₂, and/or a material having a CTE of at least one of:about 5 ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degree C.-30ppm/degree C., and greater than 30 ppm/degree C. When the pin(s) 12 aare arranged in a three-pin or three-point arrangement, the pins 12 aform a securing apparatus, such as a beamsplitter securing apparatus, acompensator securing apparatus, etc. (as best seen in the exploded viewof FIG. 7A). Alternatively, the three-pin arrangement and/or thesecuring apparatus, the beamsplitter securing apparatus, the compensatorsecuring apparatus, etc. may be used with one or more embodiments of theinterferometer 100 or the interferometer optical assembly 200 having thefirst and second materials as aforementioned, or, alternatively, may beused with one or more other embodiments of the interferometer 100 or theinterferometer optical assembly 200 comprising any material (and notbeing limited to just the first and the second materials asaforementioned).

While the beamsplitter 11 includes a first surface 71 (e.g., anoptically acting and/or optically related surface) and a second surface72 (e.g., an optically acting and/or optically related surface) (bestseen in FIG. 7A), preferably, the beamsplitter 11 further includes athird substantially transverse or substantially perpendicular (e.g.,substantially transverse or substantially perpendicular to either orboth of the first surface 71 and the second surface 72) mounting surface6 and a fourth substantially transverse or substantially perpendicular(e.g., substantially transverse or substantially perpendicular to eitheror both of the first surface 71 and the second surface 72) mountingsurface 7. The third surface 6 of the beamsplitter 11 extends betweenthe first 71 and second 72 surfaces of the beamsplitter 11 and operatesto be disposed against or adjacent to the first plate 1 of the frame 9.As best seen in FIGS. 7A-7B, preferably, the third surface 6 of thebeamsplitter 11 may include at least one coplanar landing area orsurface 56 (e.g., landing area 56 may be coplanar with the third surface6 or any other surface, such as, but not limited to the fourth surface7, against or on which it is disposed, etc.) for receipt of at least onepin 12 a thereon or thereagainst (e.g., the pin 12 a abuts (e.g.,substantially transversely, substantially perpendicularly,perpendicularly, etc.) the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, the pin 12 a is adjacent to the coplanarlanding area 56 as best seen diagrammatically in FIG. 7B, the pin 12 ais pressed against the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, etc.) to form a connection to the firstplate 1 of the frame 9 (i.e., the connection being between thebeamsplitter 11 and the first plate 1 of the frame 9). Alternatively,the landing areas or surfaces 56 may not be coplanar with, or may becoplanar with only a portion of, one or more surfaces of the one or moreoptical elements including same thereon or thereagainst. The fourthsurface 7 of the beamsplitter 11 extends between the first 71 and second72 surfaces of the beamsplitter 11 and operates to be disposed againstor adjacent to the second plate 2 of the frame 9. Preferably, the fourthsurface 7 of the beamsplitter 11 may include at least two coplanarlanding areas 56 (e.g., a second coplanar landing area 56 and a thirdcoplanar landing area 56 of the beamsplitter 11) for receipt of at leastone pin 12 a thereon or thereagainst (e.g., the pin 12 a abuts (e.g.,substantially transversely, substantially perpendicularly,perpendicularly, etc.) the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, the pin 12 a is adjacent to the coplanarlanding area 56 as best seen diagrammatically in FIG. 7B, the pin 12 ais pressed against the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, etc.) to form one or more connections tothe second plate 2 of the frame 9 (i.e., the one or more connectionsbeing between the beamsplitter 11 and the second plate 2 of the frame9).

When using the beamsplitter securing apparatus having the three-pin 12 aarrangement, the at least first coplanar landing area 56 operates toreceive at least a first pin 12 a of the three pins 12 a of thebeamsplitter securing apparatus thereon or thereagainst (e.g., the pin12 a abuts (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the coplanar landing area 56 asbest seen diagrammatically in FIG. 7B, the pin 12 a is adjacent to thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, thepin 12 a is pressed against the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, etc.) and to align with a respective firsthole 12 b of the first plate 1 of the frame 9 such that the at leastfirst pin 12 a of the three pins 12 a of the beamsplitter securingapparatus operates to be disposed in the first hole 12 b of the firstplate 1 while abutting (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the at least first coplanarlanding area 56, thereby forming an attachment between the beamsplitter11 and the first plate 1. The at least second coplanar landing area 56may operate to receive at least a second pin 12 a of the three pins 12 aof the beamsplitter securing apparatus thereon or thereagainst (e.g.,the pin 12 a abuts (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the coplanar landing area 56 asbest seen diagrammatically in FIG. 7B, the pin 12 a is adjacent to thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, thepin 12 a is pressed against the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, etc.) and to align with a respective firsthole 12 b of the second plate 2 of the frame 9 such that the at leastsecond pin 12 a of the three pins 12 a of the beamsplitter securingapparatus operates to be disposed in the first hole 12 b of the secondplate 2 while abutting (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the at least second coplanarlanding area 56, thereby forming an attachment between the beamsplitter11 and the second plate 2. The at least third coplanar landing area 56may operate to receive at least a third pin 12 a of the three pins 12 aof the beamsplitter securing apparatus thereon or thereagainst (e.g.,the pin 12 a abuts (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the coplanar landing area 56 asbest seen diagrammatically in FIG. 7B, the pin 12 a is adjacent to thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, thepin 12 a is pressed against the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, etc.) and to align with a respective secondhole 12 b of the second plate 2 such that the at least third pin 12 a ofthe three pins 12 a of the beamsplitter securing apparatus operates tobe disposed in the second hole 12 b of the second plate 2 of the frame 9while abutting (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the at least second coplanarlanding area 56, thereby forming an attachment between the beamsplitter11 and the second plate 2. Preferably, the three pins 12 a of thebeamsplitter securing apparatus: (i) have first and second ends; (ii)are sized and shaped to fit within their respective holes 12 b of theframe 9 and to abut (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) against the coplanar landingareas 56 of the beamsplitter 11 such that the beamsplitter 11 is insubstantial contact with, and/or is disposed substantially adjacent to,the first 1 and second 2 plates of the frame 9; and/or (iii) have thebonding material or shell 13 on their respective peripheries (e.g.,encapsulating the entire pin(s) 12 a, covering only a portion of thepin(s) 12 a, etc.). Preferably, the beamsplitter 11 includes the atleast one first material (e.g., at least Potassium Bromide “KBr”, atleast Calcium Fluoride “CaF₂”, at least a material having a CTE of atleast one of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C., etc.)such that the beamsplitter 11 has limited or no exposure to at least oneof bending, warping, tilting and distorting. As aforementioned, thebeamsplitter securing apparatus may be used with one or more embodimentsof the interferometer 100 or the interferometer optical assembly 200having the first and second materials as aforementioned, or,alternatively, may be used with one or more other embodiments of theinterferometer 100 or the interferometer optical assembly 200 comprisingany material (and not being limited to just the first and the secondmaterials as aforementioned).

Similarly to the general structure of the beamsplitter 11, while thecompensator 8 includes a first surface 73 (e.g., an optically actingand/or optically related surface) and a second surface 74 (e.g., anoptically acting and/or optically related surface) (best seen in FIG.7A), preferably, the compensator 8 further includes a thirdsubstantially transverse or substantially perpendicular (e.g.,substantially transverse or substantially perpendicular to either orboth of the first surface 73 and the second surface 74) mounting surface6 and a fourth substantially transverse or substantially perpendicular(e.g., substantially transverse or substantially perpendicular to eitheror both of the first surface 73 and the second surface 74) mountingsurface 7. The third surface 6 of the compensator 8 extends between thefirst 73 and second 74 surfaces of the compensator 8 and operates to bedisposed against or adjacent to the first plate 1 of the frame 9.Preferably, the third surface 6 of the compensator 8 may include atleast one coplanar landing area 56 for receipt of at least one pin 12 athereon or thereagainst (e.g., the pin 12 a abuts (e.g., substantiallytransversely, substantially perpendicularly, perpendicularly, etc.) thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, thepin 12 a is adjacent to the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, the pin 12 a is pressed against thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, etc.)to form a connection to the first plate 1 of the frame 9 (i.e., theconnection being between the compensator 8 and the first plate 1 of theframe 9). The fourth surface 7 of the compensator 8 extends between thefirst 73 and second 74 surfaces of the compensator 8 and operates to bedisposed against or adjacent to the second plate 2 of the frame 9.Preferably, the fourth surface 7 of the compensator 8 may include atleast two coplanar landing areas 56 for receipt of at least one pin 12 athereon or thereagainst (e.g., the pin 12 a abuts (e.g., substantiallytransversely, substantially perpendicularly, perpendicularly, etc.) thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, thepin 12 a is adjacent to the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, the pin 12 a is pressed against thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, etc.)to form one or more connections to the second plate 2 of the frame 9(i.e., the one or more connections being between the compensator 8 andthe first plate 1 of the frame 9).

When using the compensator securing apparatus having the three-pin 12 aarrangement, the at least first coplanar landing area 56 operates toreceive at least a first pin 12 a of the three pins 12 a of thecompensator securing apparatus thereon or thereagainst (e.g., the pin 12a abuts (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the coplanar landing area 56 asbest seen diagrammatically in FIG. 7B, the pin 12 a is adjacent to thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, thepin 12 a is pressed against the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, etc.) and to align with a respective firsthole 12 b of the first plate 1 of the frame 9 such that the at leastfirst pin 12 a of the three pins 12 a of the compensator securingapparatus operates to be disposed in the first hole 12 b of the firstplate 1 while abutting (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the at least first coplanarlanding area 56, thereby forming an attachment between the compensator 8and the first plate 1. The at least second coplanar landing area 56 mayoperate to receive at least a second pin 12 a of the three pins 12 a ofthe compensator securing apparatus thereon or thereagainst (e.g., thepin 12 a abuts (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the coplanar landing area 56 asbest seen diagrammatically in FIG. 7B, the pin 12 a is adjacent to thecoplanar landing area 56 as best seen diagrammatically in FIG. 7B, thepin 12 a is pressed against the coplanar landing area 56 as best seendiagrammatically in FIG. 7B, etc.) and to align with a respective firsthole 12 b of the second plate 2 of the frame such that the at leastsecond pin 12 a of the three pins 12 a of the compensator securingapparatus operates to be disposed in the first hole 12 b of the secondplate 2 while abutting (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the at least second coplanarlanding area 56, thereby forming an attachment between the compensator 8and the second plate 2. The at least third coplanar landing area 56 mayoperate to receive at least a third pin 12 a of the three pins 12 a ofthe compensator securing apparatus and to align with a respective secondhole 12 b of the second plate 2 such that the at least third pin 12 a ofthe three pins 12 a of the compensator securing apparatus operates to bedisposed in the second hole 12 b of the second plate 2 of the frame 9while abutting (e.g., substantially transversely, substantiallyperpendicularly, perpendicularly, etc.) the at least second coplanarlanding area 56, thereby forming an attachment between the compensator 8and the second plate 2. Preferably, the three pins 12 a of thecompensator securing apparatus: (i) have first and second ends; (ii) aresized and shaped to fit within their respective holes 12 b of the frame9 and to rest against or abut (e.g., substantially transversely,substantially perpendicularly, perpendicularly, etc.) the coplanarlanding areas 56 of the compensator 8 such that the compensator 8 is insubstantial contact with, and/or is disposed substantially adjacent to,the first 1 and second 2 plates of the frame 9; and/or (iii) have thebonding material or shell 13 on their respective peripheries (e.g.,encapsulating the entire pin(s) 12 a, covering only a portion of thepin(s) 12 a, etc.). Preferably, the compensator 8 includes the at leastone first material (e.g., at least Potassium Bromide “KBr”, at leastCalcium Fluoride “CaF₂”, at least a material having a CTE of at leastone of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C., etc.)such that the compensator 8 has limited or no exposure to at least oneof bending, warping, tilting and distorting. As aforementioned, thecompensator securing apparatus may be used with one or more embodimentsof the interferometer 100 or the interferometer optical assembly 200having the first and second materials as aforementioned, or,alternatively, may be used with one or more other embodiments of theinterferometer 100 or the interferometer optical assembly 200 comprisingany material (and not being limited to just the first and the secondmaterials as aforementioned).

As best seen in FIGS. 5 and 10-11, preferably, the mirror 5 is inwardlyfacing (e.g., facing the inside of the frame 9, facing the inside of theinterferometer optical assembly 200, etc.). Preferably, the mirror 5 hasa pin 12 a which is bonded to the first plate 1 at a corresponding pinhole 12 b and has at least two pins 12 a which are bonded to the secondplate 2 at corresponding pin holes 12 b. Said three pins 12 a arepreferentially made of the same or CTE-similar material as the frame 9.Preferably, the pins 12 a, the frame 9 and the mirrors 4, 5 are made ofthe same material. Alternatively, the mirrors 4, 5 may be substantiallysimilar or identical to each other, but differ (e.g., slightly) from theframe 9 such that the mirrors 4, 5 and the frame 9 are made of differentmaterials. In such a situation, the pins 12 a may be made either of thematerial used for the mirrors 4, 5 or of the material used for the frame9. Slight material variations may exist between at least one of theframe 9, the mirror 4, the mirror 5 and the one or more pins 12 a.Alternatively or additionally to bonding, the pins 12 a may form aconnection with the first plate 1, second plate 2 and the mirror 5 viafriction fitting or fusing (or adhering). The mirror 5 may be attachedto the frame 9, and may have a reflecting surface in a reflectingrelation with the beamsplitter 11. Preferably, the compensator 8 isdisposed between the mirror 5 and the beamsplitter 11, and the opticalassembly 200 is substantially stable regarding the reflectiverelationship between the mirror 5 and the beamsplitter 11.

Preferably, the outwardly facing (e.g., faces away from the inside or aninterior space of the frame 9, faces away from the inside of theinterferometer optical assembly 200, faces towards the retroreflector152, etc.) reflecting surface 17 of the mirror 4 operates to reflect thebeam 16 (e.g., from the retroreflector 152) and return the beam 16(e.g., to retroreflector 152). Preferably, similar to the mirror 5, theoutward facing mirror 4, and its three pins 12 a, may be made of thesame or CTE-similar material as the frame 9. As aforementioned,preferably, the outward facing reflecting mirror surface 17 isperpendicular to, or substantially perpendicular to, the beam 16 toachieve the desired optical result(s). The reflecting surface 17 of themirror 4 and/or the mirror 4 may be attached to, suspend from, and/or besuspended by, the frame 9. Preferably, the reflecting surface 17 of themirror 4 is in reflecting relation to the beamsplitter 11 through aretroreflector, such as the retroreflector 152.

Preferably, the first support member(s) 3 a and the second supportmember(s) 3 b each comprise at least one of the same material ormaterials having the identical or substantially the same coefficient ofthermal expansion. In one preferred embodiment, support member(s) 3 aand 3 b are integrally formed, machined, cast, molded, etc. with plates1 and 2, thereby forming a single part.

As best seen in FIGS. 5, 7-9 and 12-13, the protruding member 90operates to allow the monolithic interferometer optical assembly 200 tobe incorporated in one or more interferometers, such as theinterferometer 100.

The retroreflector 152 may be made of fused quartz or fine annealedPyrex (i.e., any type of borosilicate glass or glasses having a lowcoefficient of thermal expansion). As aforementioned, the retroreflector152 is designed to receive an incoming (incident) light ray (such asbeam 15 as shown in FIG. 6) and reflect the light ray off of itsreflective surfaces and out from retroreflector 152 along a path (e.g.,path of beam 16 as shown in FIG. 6) substantially parallel to theincident light ray. Of course, the incident light ray can initiallystrike any one of the reflective surfaces without bearing upon theaccuracy of the parallelism of the reflected light ray. Ifmaintaining/achieving high degrees of accuracy, i.e., parallelism of theincident and reflected light rays, is a primary purpose ofretroreflector 152, then high degrees of precision must be created andmaintained with respect to the flatness of and perpendicularity of suchreflective surfaces.

As best seen in FIGS. 12 and 15A-15F, the protruding member (e.g., theprotruding member 90, 90 a-90 f, 290, etc.) may include one or morefeatures discussed at length in co-pending U.S. patent application Ser.No. 13/036,506, filed on Feb. 28, 2011, to Bleier et al., the entiretyof which is incorporated herein by reference, or may include one or morefeatures discussed at length in U.S. Pat. No. 8,092,030, issued Jan. 10,2012, to Bleier, the entirety of which is incorporated herein byreference. For example, the protruding member 90 (also may usealternative embodiments of protruding member 90, such as, but notlimited to, protruding members 90 a, 90 b, 90 c, 90 d, 90 e, 90 f, 290,etc. as shown in FIGS. 15A-15F) may have a first portion (e.g., thefirst portion 97, 97 a, 97 b, 97 c, 97 d, 97 e, 97 f, 297, etc. as shownin FIGS. 12 and 15A-15F) extending from a surface of either the firstplate 1 or the second plate 2 of the frame 9, a second portion (e.g.,the second portion 96, 96 a, 96 b, 96 c, 96 d, 96 e, 96 f, 296, etc. asshown in FIGS. 12 and 15A-15F), and a groove (e.g., the groove 94, 94 a,94 b, 94 c, 94 d, 94 e, 94 f, 294, etc. as shown in FIGS. 12 and15A-15F) defining the first and second portions of the protruding member(e.g., the protruding member 90, 90 a-90 f, 290, etc.) on each side ofthe groove (e.g., the groove 94, 94 a, 94 b, 94 c, 94 d, 94 e, 94 f,294, etc.), the groove (e.g., the groove 94, 94 a, 94 b, 94 c, 94 d, 94e, 94 f, 294, etc.) of the protruding member (e.g., the protrudingmember 90, 90 a-90 f, 290, etc.) being constructed to dissipate and/oreliminate one or more stresses passing through the protruding member(e.g., the protruding member 90, 90 a-90 f, 290, etc.), therebypreventing the one or more stresses from affecting the interferometeroptical assembly 200. At least one of the first (e.g., the first portion97, 97 a, 97 b, 97 c, 97 d, 97 e, 97 f, 297, etc.) and said secondportions (e.g., the second portion 96, 96 a, 96 b, 96 c, 96 d, 96 e, 96f, 296, etc.) of said protruding member (e.g., the protruding member 90,90 a-90 f, 290, etc.) is at least one of: having a substantiallycircular shape and being of any geometric shape. The first portion(e.g., the first portion 97, 97 a, 97 b, 97 c, 97 d, 97 e, 97 f, 297,etc.) of the protruding member (e.g., the protruding member 90, 90 a-90f, 290, etc.) may be smaller (e.g., may have a smaller volume, have asmaller cross-section, have a small surface area, have smallerdimension(s), etc.) than the second portion (e.g., the second portion96, 96 a, 96 b, 96 c, 96 d, 96 e, 96 f, 296, etc.) of the protrudingmember (e.g., the protruding member 90, 90 a-90 f, 290, etc.) The firstportion (e.g., the first portion 97, 97 a, 97 b, 97 c, 97 d, 97 e, 97 f,297, etc.) of the protruding member (e.g., the protruding member 90, 90a-90 f, 290, etc.) may have a surface that is in contact with either thefirst plate 1 or the second plate 2 of the frame 9 and the surface ofthe first portion (e.g., the first portion 97, 97 a, 97 b, 97 c, 97 d,97 e, 97 f, 297, etc.) of the protruding member (e.g., the protrudingmember 90, 90 a-90 f, 290, etc.) may have at least one of: a smallerdiameter than a lateral cross-section and/or a bottom surface (e.g., 98,98 a-98 a, 298, etc.) of the second portion (e.g., the second portion96, 96 a, 96 b, 96 c, 96 d, 96 e, 96 f, 296, etc.) of the protrudingmember (e.g., the protruding member 90, 90 a-90 f, 290, etc.) that maybe disposed in an opening of a mount that operates to secure the opticalassembly 200 in place; and a smaller surface area than a lateralcross-section and/or a bottom surface (e.g., 98, 98 a-98 a, 298, etc.)of the second portion (e.g., the second portion 96, 96 a, 96 b, 96 c, 96d, 96 e, 96 f, 296, etc.) that is disposed in the opening of the mountthat operates to secure the optical assembly 200 in place. Theprotruding member (e.g., the protruding member 90, 90 a-90 f, 290, etc.)may be at least one of integrally formed with the surface of the firstplate 1 or the second plate 2 of the frame 9; and bonded to the surfaceof the first plate 1 or the second plate 2 of the frame 9, the bondingbeing at least one of fusing and adhering. In at least one embodiment(best seen in FIG. 15F), a top portion 211 may be included to space thegroove 294 away from the interferometer optical assembly 200.Preferably, one or more lateral cross-sections of the portion (e.g., topportion 211 as shown in FIG. 15F) of the protruding member 290 locatedbetween the groove 294 and the top surface 297 have a surface areaand/or diameter that is substantially the same as the surface areaand/or diameter of a lateral cross-section of the base portion 296 or ofthe bottom surface 298 of the member 290. While the volume of theportion (such as portion 211) may be any size, preferably, the volume ofthe portion (e.g., top portion 211 as shown in FIG. 15F) of the member290 located between the groove 294 and the top surface 297 has a volumethat is smaller than the volume of the bottom portion 296, 296 a, 296 b.

The groove (e.g., the groove 94, 94 a, 94 b, 94 c, 94 d, 94 e, 94 f,294, etc.) may include one or more features discussed at length inco-pending U.S. patent application Ser. No. 13/036,506, filed on Feb.28, 2011, to Bleier et al., the entirety of which is incorporated hereinby reference. For example, the groove (e.g., the groove 94, 94 a, 94 b,94 c, 94 d, 94 e, 94 f, 294, etc.) may be at least one of: a spacebetween the frame 9 and at least one of the second portion (e.g., thesecond portion 96, 96 a, 96 b, 96 c, 96 d, 96 e, 96 f, 296, etc.) of theprotruding member (e.g., the protruding member 90, 90 a-90 f, 290, etc.)and the mount such that the frame 9 is spaced away from the at least oneof the second portion (e.g., the second portion 96, 96 a, 96 b, 96 c, 96d, 96 e, 96 f, 296, etc.) of the protruding member (e.g., the protrudingmember 90, 90 a-90 f, 290, etc.) and the mount; and operating to achieveand/or maintain at least one of: dimensional stability, a predetermineddegree of flatness and a high degree of flatness of at least one of:about λ/10, about λ/15, about λ/20, about λ/30, between about λ/10 andabout λ/15, between about λ/10 and about λ/20, between about λ/10 andabout λ/30, between about λ/15 and about λ/20, between about λ/15 andabout λ/30 and between about λ/20 and about λ/30. The groove of theprotruding member (e.g., the protruding member 90, 90 a-90 f, 290, etc.)may extend along and/or in communication with a perimeter of the firstportion (e.g., the first portion 97, 97 a, 97 b, 97 c, 97 d, 97 e, 97 f,297, etc.) of the protruding member (e.g., the protruding member 90, 90a-90 f, 290, etc.) and may at least one of: have a substantiallycircular shape; and be of any geometric shape. The groove (e.g., thegroove 94, 94 a, 94 b, 94 c, 94 d, 94 e, 94 f, 294, etc.) of theprotruding member (e.g., the protruding member 90, 90 a-90 f, 290, etc.)may include at least one of: one or more right angles, one or moreslopes, one or more chamfered surfaces having a consistent slope, one ormore chamfered surfaces having a changing convex slope, one or morechamfered surfaces having a changing concave slope, and one or moretapers. The groove (e.g., the groove 94, 94 a, 94 b, 94 c, 94 d, 94 e,94 f, 294, etc.) may be formed at substantially a right angle such thatthe first portion (e.g., the first portion 97, 97 a, 97 b, 97 c, 97 d,97 e, 97 f, 297, etc.) of an outer surface of the protruding member(e.g., the protruding member 90, 90 a-90 f, 290, etc.) extends from thesecond portion (e.g., the second portion 96, 96 a, 96 b, 96 c, 96 d, 96e, 96 f, 296, etc.) of the protruding member (e.g., the protrudingmember 90, 90 a-90 f, 290, etc.) inwardly substantially parallel to thesurface of the first portion (e.g., the first portion 97, 97 a, 97 b, 97c, 97 d, 97 e, 97 f, 297, etc.) of the protruding member (e.g., theprotruding member 90, 90 a-90 f, 290, etc.) and a second portion of theouter surface of the protruding member (e.g., the protruding member 90,90 a-90 f, 290, etc.) extends from the first portion of the outersurface vertically substantially at a right angle and/or perpendicularto the surface of the first portion (e.g., the first portion 97, 97 a,97 b, 97 c, 97 d, 97 e, 97 f, 297, etc.) of the protruding member (e.g.,the protruding member 90, 90 a-90 f, 290, etc.).

The one or more stresses may include at least one of: connection and/orclamping stress resulting from clamping the protruding member (e.g., theprotruding member 90, 90 a-90 f, 290, etc.) to the mount, stress passingthrough the mount, stress passing through the protruding member (e.g.,the protruding member 90, 90 a-90 f, 290, etc.), sheer stress,rotational stress and stress resulting from one or more changes intemperature.

Additionally, as best seen in FIGS. 5, 7A, and 8-13, one or moreembodiments of the optical assembly 200 and/or interferometer 100 mayinclude one or more recesses 23 disposed on at least one of the firstplate 1 and the second plate 2 of the frame 9. The one or more recesses23 operate to dissipate heat from the frame 9. While the recesses 23 maybe used with any material for any of the components of the opticalassembly 200 and/or the interferometer 100, the high thermal diffusivityof the recesses 23 may preferably permit and/or aid the interactionbetween the aforementioned materials having different coefficients ofthermal expansion. As shown in FIGS. 10-11 and 13, the one or morerecesses 23 may be disposed on a plate, such as the first plate 1, andmay extend for a predetermined distance along the length of the firstplate 1. Alternatively or additionally, as best seen in FIGS. 7A, 8-9,and 12, the one or more recesses 23 or one or more other recesses 23 maybe disposed on a plate, such as the second plate 2, and may extend for apredetermined distance along the width of the second plate 2. The one ormore recesses 23 may be disposed on the first and/or second plates 1, 2in any manner known to those skilled in the art, such as, but notlimited to, etching, carving, molding, cutting, etc.

In accordance with at least a further aspect of the present invention,an interferometer 100 may include a radiation source (such as theradiation source 10, 110, etc.); a beamsplitter 11 having a firstsurface and a second surface, the beamsplitter 11 including at least onefirst material; a frame 9 having a first plate 1 and a second plate 2having the beamsplitter 11 extending therebetween; a retroreflector(e.g., such as the retroreflector 152) disposed externally to the frame9, the retroreflector (e.g., such as the retroreflector 152) operatingto move relative to the frame 9; a first mirror 5 attached to the frame9 and having a reflecting surface in a first direct reflecting relationwith the beamsplitter 11; and a second mirror (e.g., the mirror surface17) attached to the frame 9 and having a reflecting surface in a seconddirect reflecting relation with the retroreflector (e.g., such as theretroreflector 152). Preferably, the retroreflector (e.g., such asretroreflector 152) has a retroreflection relation with both thebeamsplitter 11 and the second mirror (e.g., the mirror surface 17).Preferably, the frame 9 is made of at least a second material that isdifferent from the at least one first material, and the at least onefirst material has a coefficient of thermal expansion that is identicalto or substantially similar to a coefficient of thermal expansion of theat least second material such that the beamsplitter 11 has limited or noexposure to at least one of bending, warping, tilting and distorting.One or more aforementioned features of the interferometer opticalassembly 200 may be incorporated into one or more embodiments of theinterferometer 100 described herein.

The manner of mounting described herein is an improvement over priormounting manners and is equally good, if not better, at preventingdistortion of one or more optical components of the interferometeroptical assembly 200 and/or the interferometer 100 as described herein.The method of mounting one or more components of the interferometeroptical assembly 200 and/or the interferometer 100 as described hereinachieves the advantage that one or more optical components of theassembly 200 and/or interferometer 100 have limited or no exposure to atleast one of bending, warping, tilting and distorting. The method ofmounting includes the steps of disposing a beamsplitter 11 having afirst surface 71 and a second surface 72 in between a first plate 1 anda second plate 2 of a frame 9 such that the beamsplitter 11 extendsbetween the first plate 1 and the second plate 2, the beamsplitter 11comprising at least one first material, wherein (i) the frame includesat least a second material that is different from the at least one firstmaterial; and (ii) the at least one first material has a coefficient ofthermal expansion that is identical to or substantially similar to acoefficient of thermal expansion of the at least second material suchthat the beamsplitter 11 has limited or no exposure to at least one ofbending, warping, tilting and distorting. One or more structuralfeatures of the one or more components of the interferometer opticalassembly 200 and/or the interferometer 100 may be incorporated into themethod of mounting same. For example, preferably, the at least one firstmaterial includes Potassium Bromide (“KBr”), Calcium Fluoride (“CaF₂”)and/or a material having a high CTE (e.g., having a CTE of at least oneof: about 5 ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degreeC.-30 ppm/degree C., greater than 30 ppm/degree C., etc.), and the atleast one second material includes at least one of Zinc, Aluminum,Magnesium, an Aluminum-Zinc or a Zinc-Aluminum alloy.

The method further includes kinematically mounting the beamsplitter 11to the frame 9 using a beamsplitter securing apparatus comprising threepins 12 a each having a first end and a second end. Preferably, thethree pins 12 a of the beamsplitter securing apparatus include at leastthe first material, e.g., Potassium Bromide (“KBr”), Calcium Fluoride(“CaF₂”), a material having a CTE of at least one of: about 5 ppm/degreeC.-about 10 ppm/degree C., about 10 ppm/degree C.-30 ppm/degree C., andgreater than 30 ppm/degree C., etc. The method may include disposing abonding material on at least a periphery of each of the three pins 12 aof the beamsplitter securing apparatus, the bonding material operatingto bond the three pins 12 a to the beamsplitter 11 and at least one ofthe first plate 1 and the second plate 2 of the frame 9. The method mayfurther include: (i) having the beamsplitter 11 further include a thirdsurface 6 and a fourth surface 7, the third surface 6 and the fourthsurface 7 of the beamsplitter 11 extending between the first 71 andsecond 72 surfaces of the beamsplitter 11 on opposite ends of thebeamsplitter 11; (ii) disposing the third surface 6 of the beamsplitter11 against (or adjacent to) the first plate 1 of the frame 9; and (iii)disposing the fourth surface 7 of the beamsplitter 11 against (oradjacent to) the second plate 2 of the frame 9.

The method may further include having the beamsplitter 11 furtherinclude at least a first landing area 56 (which may substantiallyparallel to a surface, such as the surface 6; may be coplanar with asurface, such as the surface 6; may not be coplanar with, or may only becoplanar with, a portion of one or more surfaces of the one or moreoptical elements or components of the interferometer optical assembly200; may be substantially parallel to a portion of one or more surfacesof the one or more optical elements or components of the interferometeroptical assembly 200; etc.) on or against the third surface 6 of thebeamsplitter 11 and at least a second landing area 56 and a thirdlanding area 56 (which may be substantially parallel to a surface, suchas the surface 7; may be coplanar with a surface, such as the surface 7;may not be coplanar with, or may only be coplanar with, a portion of oneor more surfaces of the one or more optical elements or components ofthe interferometer optical assembly 200; may be substantially parallelto a portion of one or more surfaces of the one or more optical elementsor components of the interferometer optical assembly 200; etc.) on oragainst the fourth surface 7 of the beamsplitter 11; disposing the firstend of at least a first pin 12 a of the three pins 12 a of thebeamsplitter securing apparatus onto or against the at least firstlanding area 56 of the beamsplitter 11; disposing the second end of theat least first pin 12 a into a respective first hole 12 b of the firstplate 1 such that the at least first pin 12 a of the three pins 12 a ofthe beamsplitter securing apparatus operates to be disposed on oragainst the at least first landing area 56 of the beamsplitter 11 and inthe first hole 12 b of the first plate 1, thereby forming an attachmentbetween the beamsplitter 11 and the first plate 1; disposing the firstend of at least a second pin 12 a of the three pins 12 a of thebeamsplitter securing apparatus onto or against the at least secondlanding area 56 of the beamsplitter 11; disposing the second end of theat least second pin 12 a into a respective first hole 12 b of the secondplate 2 such that the at least second pin 12 a of the three pins 12 a ofthe beamsplitter securing apparatus operates to be disposed on oragainst the at least second landing area 56 of the beamsplitter 11 andin the first hole 12 b of the second plate 2, thereby forming anattachment between the beamsplitter 11 and the second plate 2; disposingthe first end of at least a third pin 12 a of the three pins 12 a of thebeamsplitter securing apparatus on or against the at least third landingarea 56 of the beamsplitter 11; and disposing the second end of the atleast third pin 12 a into a respective second hole 12 b of the secondplate 2 such that the at least third pin 12 a of the three pins 12 a ofthe beamsplitter securing apparatus operates to be disposed on oragainst the at least third landing area 56 of the beamsplitter 11 and inthe second hole 12 b of the second plate 2, thereby forming anattachment between the beamsplitter 11 and the second plate 2. Themethod may further include sizing and shaping the three pins 12 a of thebeamsplitter securing apparatus to fit within their respective holes 12b of the first 1 and/or second plates 2 of the frame 9 and to bedisposed on or against the one or more landing areas 56 of thebeamsplitter 11 such that the beamsplitter 11 is in substantial contactwith, and/or is disposed substantially adjacent to, the first and secondplates of the frame. The bonding material or shell 13 may be disposed onat least a periphery of each of the three pins 12 a of the beamsplittersecuring apparatus, the bonding material 13 operating to bond the threepins 12 a of the beamsplitter securing apparatus to the beamsplitter 11and at least one of the first plate 1 and the second plate 2 of theframe 9.

The method may further include disposing a compensator 8 inside/on/tothe frame 9 and connecting the compensator 8 in the same or similarfashion to the way the beamsplitter 11 is connected or disposed in/on/tothe frame 9 as described above. For example, a compensator securingapparatus having three pins 12 a each having a first end and a secondend may be used in the same or similar fashion as the beamsplittersecuring apparatus to kinematically mount the compensator 8 to the frame9. Preferably, the compensator 8 includes the at least one firstmaterial (e.g., KBr, CaF₂, a material having a CTE of at least one of:about 5 ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degree C.-30ppm/degree C., and greater than 30 ppm/degree C., etc.) such that thecompensator 8 has limited or no exposure to at least one of bending,warping, tilting and distorting, and the three pins 12 a of thecompensator securing apparatus, preferably, include at least the firstmaterial, such as, but not limited to, Potassium Bromide, CalciumFluoride, etc.

The bonding material or shell 13 may be disposed on at least a peripheryof each of the three pins 12 a of the compensator securing apparatus,the bonding material 13 operating to bond the three pins 12 a of thecompensator securing apparatus to the compensator 8 and at least one ofthe first plate 1 and the second plate 2 of the frame 9. The compensator8 may further include a third surface 6 and a fourth surface 7, thethird surface 6 and the fourth surface 7 of the compensator 8 extendingbetween the first 73 and second 74 surfaces of the compensator 8 onopposite ends of the compensator 8, and the method may further includedisposing the third surface 6 of the compensator 8 against or adjacentto the first plate 1 of the frame 9; and disposing the fourth surface 7of the compensator 8 against or adjacent to the second plate 2 of theframe 9. The compensator 8 may further include at least a first landingarea 56 (which may be coplanar with a surface, such as the surface 6;may be substantially parallel to a surface, such as the surface 6; maynot be coplanar with, or may only be coplanar with, a portion of one ormore surfaces of the one or more optical elements or components of theinterferometer optical assembly 200; may be substantially parallel to aportion of one or more surfaces of the one or more optical elements orcomponents of the interferometer optical assembly; etc.) on or againstthe third surface 6 of the compensator 8 and at least a second landingarea 56 and a third landing area 56 (which may be substantially parallelto a surface, such as the surface 7; may be coplanar with a surface,such as the surface 7; may not be coplanar with, or may only be coplanarwith, a portion of one or more surfaces of the one or more opticalelements or components of the interferometer optical assembly 200; maybe substantially parallel to a portion of one or more surfaces of theone or more optical elements or components of the interferometer opticalassembly 200; etc.) in communication with the fourth surface 7 of thecompensator 8, and the method may include disposing the first end of atleast a first pin 12 a of the three pins 12 a of the compensatorsecuring apparatus on or against the at least first landing area 56 ofthe compensator 8; disposing the second end of the at least first pin 12a of the three pins 12 a of the compensator securing apparatus into arespective first hole 12 b of the first plate 1 such that the at leastfirst pin 12 a of the three pins 12 a of the compensator securingapparatus operates to be disposed on or against the at least firstlanding area 56 of the compensator 8 and in the first hole 12 b of thefirst plate 1, thereby forming an attachment between the compensator 8and the first plate 1; disposing the first end of at least a second pin12 a of the three pins 12 a of the compensator securing apparatus on oragainst the at least second landing area 56 of the compensator 8;disposing the second end of the at least second pin 12 a of the threepins 12 a of the compensator securing apparatus into a respective firsthole 12 b of the second plate 2 such that the at least second pin 12 aof the three pins 12 a of the compensator securing apparatus operates tobe disposed on or against the at least second landing area 56 of thecompensator 8 and in the first hole 12 b of the second plate 2, therebyforming an attachment between the compensator 8 and the second plate 2;disposing the first end of at least a third pin 12 a of the three pins12 a of the compensator securing apparatus on or against the at leastthird landing area 56 of the compensator 8; and disposing the second endof the at least third pin 12 a of the three pins 12 a of the compensatorsecuring apparatus into a respective second hole 12 b of the secondplate 2 such that the at least third pin 12 a of the three pins 12 a ofthe compensator securing apparatus operates to be disposed on or againstthe at least third landing area 56 of the compensator 8 and in thesecond hole 12 b of the second plate 2, thereby forming an attachmentbetween the compensator 8 and the second plate 2. The three pins 12 a ofthe compensator securing apparatus may be sized and shaped to fit withintheir respective holes 12 b of the first 1 and/or second 2 plates of theframe 9 and on or against the one or more landing areas 56 of thecompensator 8 such that the compensator 8 is in substantial contactwith, and/or is disposed substantially adjacent to, the first 1 andsecond 2 plates of the frame 9.

The method may further include at least one of bonding a first supportmember 3 a between a first portion of the first plate 1 and a firstportion of the second plate 2; and bonding a second support member 3 bbetween a second portion of the first plate 1 and a second portion ofthe second plate 2. The first support member 3 a and the second supportmember 3 b may each include at least one of the same material ormaterials having the identical or substantially the same coefficient ofthermal expansion. In at least one embodiment, there may be a pluralityof the first support members 3 a and/or second support members 3 b.

The method may further include attaching a mirror 5 to the frame 9 suchthat the mirror 5 has a reflecting surface in a reflecting relation withthe beamsplitter 11, wherein the compensator 8 is disposed between themirror 5 and the beamsplitter 11 and the optical assembly 200 issubstantially stable regarding the reflective relationship between themirror 5 and the beamsplitter 11. One may further at least one of: (i)attach a second mirror (e.g., the mirror 4, and/or a portion of themirror 4, such as, but not limited to, the reflecting surface 17 of themirror 4) to the frame 9 such that the second mirror 4 has a reflectingsurface 17 facing away from an interior space of the frame 9, and thereflecting surface 17 of the mirror 4 is in reflecting relation to thebeamsplitter 11 through a retroreflector (e.g., the retroreflector 152);and (ii) dispose a protruding member 90 (or 90 a-90 f, 290, etc.) on theframe 9 such that the protruding member 90 (or 90 a-90 f, 290, etc.) hasa first portion extending from a surface of either the first plate 1 orthe second plate 2 of the frame 9, a second portion 96 (or 96 a-96 f,296, etc.), and a groove 94 (or 94 a-94 f, 294, etc.) defining the first97 (or 97 a-97 f, 297, etc.) and second 96 (or 96 a-96 f, 296, etc.)portions of the protruding member 90 (or 90 a-90 f, 290, etc.) on eachside of the groove 94 (or 94 a-94 f, 294, etc.), the groove 94 (or 94a-94 f, 294, etc.) of the protruding member 90 (or 90 a-90 f, 290, etc.)being constructed to dissipate and/or eliminate one or more stressespassing through the protruding member 90 (or 90 a-90 f, 290, etc.),thereby preventing the one or more stresses from affecting the opticalassembly 200.

Additionally, one may align one or more of the first plate 1, the secondplate 2, the first support member 3 a, the second support member 3 b,the mirror 5, the second mirror 4 and/or the reflecting surface 17 ofthe mirror 4, the beamsplitter 11, the compensator 8, the three pins 12a of the beamsplitter securing apparatus and the three pins 12 a of thecompensator securing apparatus before locking the alignment in placewith at least one of friction, fusing (or adhering), adhesive force(s)and bonding.

It will also be seen that the manner of mounting described hereinachieves substantial rigidity between the components of theinterferometer 100, including the interferometer optical assembly 200.

The present invention also may be used in conjunction with any suitableoptical assembly including, but not limited to, optical assemblystructures, interferometers, and/or retroreflectors such as thosedisclosed in U.S. Pat. Nos. 5,335,111; 5,949,543; 6,141,101; 6,473,185;6,729,735; 6,752,503; 6,786,608; 6,827,455; 6,945,661; 7,168,817;7,995,208; 8,092,030 to Bleier; U.S. Pat. No. 7,268,960 to Vishnia; andU.S. application Ser. No. 12/505,279, filed on Jul. 17, 2009, (whichissued as U.S. Pat. No. 8,205,852 on Jun. 26, 2012 ), and Ser. No.13/036,506, filed on Feb. 28, 2011, (presently pending), each of whichpatents and applications are incorporated by reference herein in theirentireties. One construction for a hollow retroreflector is as disclosedin U.S. Pat. No. 3,663,084 to Morton S. Lipkins.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention.

What is claimed is:
 1. An optical assembly for use with a precisioninstrument, comprising: a frame comprising a first plate and a secondplate; an optical element extending between the first plate of the frameand the second plate of the frame and the optical element having a firstsurface, a second surface, a third surface, a fourth surface, at least afirst landing point or area on or against the third surface of theoptical element, at least a second landing point or area on or againstthe fourth surface of the optical element, and at least a third landingpoint or area on or against the fourth surface of the optical element,the third surface of the optical element extending between the first andsecond surfaces of the optical element and operating to be disposedagainst or adjacent to the first plate of the frame and the fourthsurface of the optical element extending between the first and secondsurfaces of the optical element and operating to be disposed against oradjacent to the second plate of the frame; and an optical elementsecuring apparatus comprising three pins each having a first end and asecond end, the three pins operating to mount the optical element to theframe such that the optical element has limited or no exposure to atleast one of bending, warping, tilting and distorting, wherein: (i) theat least first landing point or area of the optical element operates toreceive at least a first pin of the three pins of the optical elementsecuring apparatus thereon or thereagainst and to align with arespective first hole of the first plate such that the at least firstpin of the three pins of the optical element securing apparatus operatesto also be disposed in the first hole of the first plate, therebyforming an attachment between the optical element and the first plate;(ii) the at least second landing point or area of the optical elementoperates to receive at least a second pin of the three pins of theoptical element securing apparatus thereon or thereagainst and to alignwith a respective first hole of the second plate such that the at leastsecond pin of the three pins of the optical element securing apparatusoperates to also be disposed in the first hole of the second plate,thereby forming an attachment between the optical element and the secondplate; and (iii) the at least third landing point or area of the opticalelement operates to receive at least a third pin of the three pins ofthe optical element securing apparatus thereon or thereagainst and toalign with a respective second hole of the second plate such that the atleast third pin of the three pins of the optical element securingapparatus operates to also be disposed in the second hole of the secondplate, thereby forming an attachment between the optical element and thesecond plate.
 2. The optical assembly of claim 1, wherein at least oneof: (i) at least one of the at least first landing point or area of theoptical element, the at least second landing point or area of theoptical element and the at least third landing point or area of theoptical element is at least one of: coplanar, coplanar with the thirdsurface of the optical element, not coplanar, not coplanar with thethird surface of the optical element, coplanar with the fourth surfaceof the optical element, not coplanar with the fourth surface of theoptical element, coplanar with one or more surfaces of the opticalelement, not coplanar with one or more surfaces of the optical element,substantially parallel with the third surface of the optical element,substantially parallel with the fourth surface of the optical element,and substantially parallel with one or more surfaces of the opticalelement; (ii) the three pins of the optical element securing apparatusare sized and shaped to fit within their respective holes of the firstand/or second plates of the frame and to be disposed on or against, andwhose ends contact, their respective landing points or areas of theoptical element such that the optical element is in substantial contactwith, and/or is disposed substantially adjacent to, the first and secondplates of the frame; (iii) the three pins of the optical elementsecuring apparatus each include bonding material on at least a peripherythereof, the bonding material operating to bond the three pins of theoptical element securing apparatus to the optical element and at leastone of the first plate and the second plate of the frame; (iv) the threepins of the optical element securing apparatus and the optical elementcomprise the same material(s); (v) the optical element and at least oneof the first plate and the second plate of the frame comprise materialshaving different coefficients of thermal expansion; (vi) at least one ofthe optical element, the optical element securing apparatus and thethree pins of the optical element securing apparatus each comprise atleast one of: Potassium Bromide (“KBr”), Calcium Fluoride (“CaF₂”), anda material having a CTE of at least one of: about 5 ppm/degree C.-about10 ppm/degree C., about 10 ppm/degree C.-30 ppm/degree C., and greaterthan 30 ppm/degree C.; (vii) the frame comprises at least one of Zinc,Aluminum, Magnesium, an Aluminum-Zinc or a Zinc-Aluminum alloy; (viii)the frame includes one or more recesses on a surface of at least one ofthe first plate and the second plate, the one or more recesses operatingto dissipate heat; (ix) at least one of the optical element, the opticalelement securing apparatus and the three pins of the optical elementsecuring apparatus comprise a first material; and at least one of thefirst plate and the second plate of the frame comprise a secondmaterial; the first and second materials having one or more coefficientsof thermal expansion that are at least one of identical, substantiallythe same, and as close as practicable to each other; (x) when the firstand second materials have one or more coefficients of thermal expansionthat are as close as practicable to each other and when the firstmaterial comprises at least one of: Potassium Bromide (“KBr”), CalciumFluoride (“CaF₂”), and a material having a CTE of at least one of: about5 ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degree C.-30ppm/degree C., and greater than 30 ppm/degree C., the second materialcomprises at least one of: Zinc, Aluminum, Magnesium, an Aluminum-Zincor a Zinc-Aluminum alloy, and a material having a CTE of at least oneof: about 23 ppm/degree Celsius, higher than 23 ppm/degree Celsius,about 23.4 to about 23.6 ppm/degree Celsius, about 23 to about 27ppm/degree Celsius, and about 23 to about 28 ppm/degree Celsius; and(xi) the optical element comprises at least one of a beamsplitter and acompensator.
 3. The optical assembly of claim 1, further comprising atleast one of: (i) a first support member bonded between a first portionof the first plate and a first portion of the second plate, and/or asecond support member bonded between a second portion of the first plateand a second portion of the second plate; and (ii) a first supportmember disposed between a first portion of the first plate and a firstportion of the second plate and a second support member disposed betweena second portion of the first plate and a second portion of the secondplate, the first and second support members being integrally formed withthe first plate and the second plate, thereby forming a single part. 4.The optical assembly of claim 3, wherein the first support member andthe second support member each comprise at least one of the samematerial or materials having one or more coefficients of thermalexpansion that are at least one of identical, substantially the same,and as close as practicable to each other.
 5. The optical assembly ofclaim 4, further comprising a mirror attached to the frame, the mirrorhaving a reflecting surface in a reflecting relation with the opticalelement, wherein at least one of: (i) the optical assembly issubstantially stable regarding the reflective relationship between themirror and the optical element; and (ii) when the material or materialsof the first support member and the material or materials of the secondsupport member have one or more coefficients of thermal expansion thatare as close as practicable to each other and when the material ormaterials of one of the first and second support members comprise atleast one of: Potassium Bromide (“KBr”), Calcium Fluoride (“CaF₂”), anda material having a CTE of at least one of: about 5 ppm/degree C.-about10 ppm/degree C., about 10 ppm/degree C.-30 ppm/degree C., and greaterthan 30 ppm/degree C., the material or materials of the other of thefirst and second support members comprise at least one of: Zinc,Aluminum, Magnesium, an Aluminum-Zinc or a Zinc-Aluminum alloy, and amaterial having a CTE of at least one of: about 23 ppm/degree Celsius,higher than 23 ppm/degree Celsius, about 23.4 to about 23.6 ppm/degreeCelsius, about 23 to about 27 ppm/degree Celsius, and about 23 to about28 ppm/degree Celsius.
 6. The optical assembly of claim 5, furthercomprising a second mirror attached to the frame, the second mirrorhaving a reflecting surface facing away from an interior space of theframe, the second mirror being in reflecting relation to the opticalelement through a retroreflector, wherein at least one of: (i) the frameincludes at least another hole that operates to receive at least oneadditional pin therein; (ii) the mirror and the second mirror eachinclude at least one landing point or area that operates to receive theat least one additional pin thereon or thereagainst, thereby creatingrespective attachments between the frame and the mirror and the secondmirror when the at least one additional pin is disposed in the at leastanother hole of the frame and is disposed on or against the at least onelanding point or area of the mirror and/or the at least one landingpoint or area of the second mirror; (iii) the at least one additionalpin comprises the same material as the material used for at least one ofthe frame, the mirror and the second mirror; and (iv) the mirror and thesecond mirror are made of at least one of: the same material as eachother but different from the frame, the same material as the frame, andthe same material as the frame and each other.
 7. The optical assemblyof claim 6, further comprising a protruding member having a firstportion extending from a surface of either the first plate or the secondplate of the frame, a second portion, and a groove defining the firstand second portions of the protruding member on each side of the groove,the groove of the protruding member being constructed to dissipateand/or eliminate one or more stresses passing through the protrudingmember, thereby preventing the one or more stresses from affecting theoptical assembly.
 8. The optical assembly of claim 7, wherein at leastone of: (i) at least one of the first and said second portions of saidprotruding member is at least one of: having a substantially circularshape and being of any geometric shape; (ii) the first portion of theprotruding member is smaller than the second portion of the protrudingmember; (iii) the first portion of the protruding member has a surfacethat is in contact with either the first plate or the second plate ofthe frame and the surface of the first portion of the protruding memberhas at least one of: a smaller diameter than a lateral cross-sectionand/or a bottom surface of the second portion of the protruding memberthat is disposed in an opening of a mount that operates to secure theoptical assembly in place; and a smaller surface area than a lateralcross-section and/or a bottom surface of the second portion that isdisposed in the opening of the mount that operates to secure the opticalassembly in place; (iv) the first portion of the protruding member has asmaller volume than the second portion of the protruding member; (v) thegroove is at least one of: a space between the frame and at least one ofthe second portion of the protruding member and the mount such that theframe is spaced away from the at least one of the second portion of theprotruding member and the mount; and operating to achieve and/ormaintain at least one of: dimensional stability, a predetermined degreeof flatness and a high degree of flatness of at least one of: aboutλ/10, about λ/15, about λ/20, about λ/30, between about λ/10 and aboutλ/15, between about λ/10 and about λ/20, between about λ/10 and aboutλ/30, between about λ/15 and about λ/20, between about λ/15 and aboutλ/30 and between about λ/20 and about λ/30; (vi) the protruding memberis at least one of integrally formed with the surface of the first plateor the second plate; and bonded to the surface of the first plate or thesecond plate, the bonding being at least one of fusing and adhering;(vii) the groove of the protruding member extends along and/or incommunication with a perimeter of the first portion of the protrudingmember and is at least one of: having a substantially circular shape;and being of any geometric shape; (viii) the groove of the protrudingmember includes at least one of: one or more right angles, one or moreslopes, one or more chamfered surfaces having a consistent slope, one ormore chamfered surfaces having a changing convex slope, one or morechamfered surfaces having a changing concave slope, and one or moretapers; (ix) the groove is formed at substantially a right angle suchthat a first portion of an outer surface of the protruding memberextends from the second portion of the protruding member inwardlysubstantially parallel to the surface of the first portion of theprotruding member and a second portion of the outer surface of theprotruding member extends from the first portion of the outer surfacevertically substantially at a right angle and/or perpendicular to thesurface of the first portion of the protruding member; and (x) the oneor more stresses comprises at least one of: connection and/or clampingstress resulting from clamping the protruding member to the mount,stress passing through the mount, stress passing through the protrudingmember, sheer stress, rotational stress, and stress resulting from oneor more changes in temperature.
 9. The optical assembly of claim 8,further comprising one or more recesses disposed on a surface of atleast one of the first plate and the second plate, the one or morerecesses operating to dissipate heat.
 10. An interferometer comprising:a radiation source; a frame comprising a first plate and a second plate;a beamsplitter extending between the first plate of the frame and thesecond plate of the frame and the beamsplitter having a first surface, asecond surface, a third surface, a fourth surface, at least a firstlanding point or area on or against the third surface of thebeamsplitter, at least a second landing point or area on or against thefourth surface of the beamsplitter, and at least a third landing pointor area on or against the fourth surface of the beamsplitter, the thirdsurface of the beamsplitter extending between the first and secondsurfaces of the beamsplitter and operating to be disposed against oradjacent to the first plate of the frame and the fourth surface of thebeamsplitter extending between the first and second surfaces of thebeamsplitter and operating to be disposed against or adjacent to thesecond plate of the frame; a retroreflector disposed externally to theframe, the retroreflector operating to move relative to the frame; afirst mirror attached to the frame and having a reflecting surface in afirst direct reflecting relation with the beamsplitter; a second mirrorattached to the frame and having a reflecting surface in a second directreflecting relation with the retroreflector; and a beamsplitter securingapparatus comprising three pins each having a first end and a secondend, the three pins operating to mount the beamsplitter to the framesuch that the beamsplitter has limited or no exposure to at least one ofbending, warping, tilting and distorting, wherein: (i) theretroreflector has a retroreflection relation with both the beamsplitterand the second mirror; (ii) the at least first landing point or area ofthe beamsplitter operates to receive at least a first pin of the threepins of the beamsplitter securing apparatus thereon or thereagainst andto align with a respective first hole of the first plate such that theat least first pin of the three pins of the beamsplitter securingapparatus operates to also be disposed in the first hole of the firstplate, thereby forming an attachment between the beamsplitter and thefirst plate; (iii) the at least second landing point or area of thebeamsplitter operates to receive at least a second pin of the three pinsof the beamsplitter securing apparatus thereon or thereagainst and toalign with a respective first hole of the second plate such that the atleast second pin of the three pins of the beamsplitter securingapparatus operates to also be disposed in the first hole of the secondplate, thereby forming an attachment between the beamsplitter and thesecond plate; and (iv) the at least third landing point or area of thebeamsplitter operates to receive at least a third pin of the three pinsof the beamsplitter securing apparatus thereon or thereagainst and toalign with a respective second hole of the second plate such that the atleast third pin of the three pins of the beamsplitter securing apparatusoperates to also be disposed in the second hole of the second plate,thereby forming an attachment between the beamsplitter and the secondplate.
 11. The interferometer of claim 10, further comprising: acompensator extending between the first plate of the frame and thesecond plate of the frame and the compensator having a first surface, asecond surface, a third surface, a fourth surface, at least a firstlanding point or area on or against the third surface of thecompensator, at least a second landing point or area on or against thefourth surface of the compensator, and at least a third landing point orarea on or against the fourth surface of the compensator, the thirdsurface of the compensator extending between the first and secondsurfaces of the compensator and operating to be disposed against oradjacent to the first plate of the frame and the fourth surface of thecompensator extending between the first and second surfaces of thecompensator and operating to be disposed against or adjacent to thesecond plate of the frame; and a compensator securing apparatuscomprising three pins each having a first end and a second end, thethree pins operating to mount the compensator to the frame such that thecompensator has limited or no exposure to at least one of bending,warping, tilting and distorting, wherein: (i) the at least first landingpoint or area of the compensator operates to receive at least a firstpin of the three pins of the compensator securing apparatus thereon orthereagainst and to align with a respective first hole of the firstplate such that the at least first pin of the three pins of thecompensator securing apparatus operates to also be disposed in the firsthole of the first plate, thereby forming an attachment between thecompensator and the first plate; (ii) the at least second landing pointor area of the compensator operates to receive at least a second pin ofthe three pins of the compensator securing apparatus thereon orthereagainst and to align with a respective first hole of the secondplate such that the at least second pin of the three pins of thecompensator securing apparatus operates to also be disposed in the firsthole of the second plate, thereby forming an attachment between thecompensator and the second plate; and (iii) the at least third landingpoint or area of the compensator operates to receive at least a thirdpin of the three pins of the compensator securing apparatus thereon orthereagainst and to align with a respective second hole of the secondplate such that the at least third pin of the three pins of thecompensator securing apparatus operates to also be disposed in thesecond hole of the second plate, thereby forming an attachment betweenthe compensator and the second plate.
 12. The interferometer of claim11, wherein at least one of: (i) at least one of the at least firstlanding point or area of the beamsplitter, the at least second landingpoint or area of the beamsplitter and the at least third landing pointor area of the beamsplitter is at least one of: coplanar, coplanar withthe third surface of the beamsplitter, not coplanar, not coplanar withthe third surface of the beamsplitter, coplanar with the fourth surfaceof the beamsplitter, not coplanar with the fourth surface of thebeamsplitter, coplanar with one or more surfaces of the beamsplitter,not coplanar with one or more surfaces of the beamsplitter,substantially parallel with the third surface of the beamsplitter,substantially parallel with the fourth surface of the beamsplitter, andsubstantially parallel with one or more surfaces of the beamsplitter;(ii) the three pins of the beamsplitter securing apparatus are sized andshaped to fit within their respective holes of the first and/or secondplates of the frame and to be disposed on or against, and whose endscontact, their respective landing points or areas of the beamsplittersuch that the beamsplitter is in substantial contact with, and/or isdisposed substantially adjacent to, the first and second plates of theframe; (iii) at least one of the at least first landing point or area ofthe compensator, the at least second landing point or area of thecompensator and the at least third landing point or area of thecompensator is at least one of: coplanar, coplanar with the thirdsurface of the compensator, not coplanar, not coplanar with the thirdsurface of the compensator, coplanar with the fourth surface of thecompensator, not coplanar with the fourth surface of the compensator,coplanar with one or more surfaces of the compensator, not coplanar withone or more surfaces of the compensator, substantially parallel with thethird surface of the compensator, substantially parallel with the fourthsurface of the compensator, and substantially parallel with one or moresurfaces of the compensator; (iv) the three pins of the compensatorsecuring apparatus are sized and shaped to fit within their respectiveholes of the first and/or second plates of the frame and to be disposedon or against, and whose ends contact, their respective landing pointsor areas of the compensator such that the compensator is in substantialcontact with, and/or is disposed substantially adjacent to, the firstand second plates of the frame; (v) the three pins of the beamsplittersecuring apparatus each include bonding material on at least a peripherythereof, the bonding material operating to bond the three pins of thebeamsplitter securing apparatus to the beamsplitter and at least one ofthe first plate and the second plate of the frame; (vi) the three pinsof the compensator securing apparatus each include bonding material onat least a periphery thereof, the bonding material operating to bond thethree pins of the compensator securing apparatus to the compensator andat least one of the first plate and the second plate of the frame; (vii)at least one of: the frame includes at least another hole that operatesto receive at least one additional pin therein; the mirror and thesecond mirror each include at least one landing point or area thatoperates to receive the at least one additional pin thereon orthereagainst, thereby creating respective attachments between the frameand the mirror and the second mirror when the at least one additionalpin is disposed in the at least another hole of the frame and isdisposed on or against the at least one landing point or area of themirror and/or the at least one landing point or area of the secondmirror; the at least one additional pin comprises the same material asthe material used for at least one of the frame, the mirror and thesecond mirror; and the mirror and the second mirror are made of at leastone of: the same material as each other, the same material as the frameand the same material as the frame and each other; (viii) theinterferometer further comprises at least one of: a first support memberbonded between a first portion of the first plate and a first portion ofthe second plate and/or a second support member bonded between a secondportion of the first plate and a second portion of the second plate; anda first support member disposed between a first portion of the firstplate and a first portion of the second plate and a second supportmember disposed between a second portion of the first plate and a secondportion of the second plate, the first and second support members beingintegrally formed with the first plate and the second plate, therebyforming a single part; (ix) the first support member and the secondsupport member each comprise at least one of the same material ormaterials having one or more coefficients of thermal expansion that areat least one of identical, substantially the same, and as close aspracticable to each other; (x) the compensator is disposed between thefirst mirror and the beamsplitter and the interferometer issubstantially stable regarding the reflective relationship between themirror and the beamsplitter; (xi) the frame further comprises aprotruding member having a first portion extending from a surface ofeither the first plate or the second plate of the frame, a secondportion, and a groove defining the first and second portions of theprotruding member on each side of the groove, the groove of theprotruding member being constructed to dissipate and/or eliminate one ormore stresses passing through the protruding member, thereby preventingthe one or more stresses from affecting the optical assembly; and (xii)when the material or materials of the first support member and thematerial or materials of the second support member have one or morecoefficients of thermal expansion that are as close as practicable toeach other and when the material or materials of one of the first andsecond support members comprise at least one of: Potassium Bromide(“KBr”), Calcium Fluoride (“CaF₂”), and a material having a CTE of atleast one of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C., thematerial or materials of the other of the first and second supportmembers comprise at least one of: Zinc, Aluminum, Magnesium, anAluminum-Zinc or a Zinc-Aluminum alloy, and a material having a CTE ofat least one of: about 23 ppm/degree Celsius, higher than 23 ppm/degreeCelsius, about 23.4 to about 23.6 ppm/degree Celsius, about 23 to about27 ppm/degree Celsius, and about 23 to about 28 ppm/degree Celsius. 13.The interferometer of claim 11, wherein at least one of: (i) at leastone of the beamsplitter and the compensator comprises at least one of:Potassium Bromide (“KBr”), Calcium Fluoride (“CaF₂”), and a materialhaving a CTE of at least one of: about 5 ppm/degree C.-about 10ppm/degree C., about 10 ppm/degree C.-30 ppm/degree C., and greater than30 ppm/degree C.; (ii) the three pins of the beamsplitter securingapparatus at least one of: each comprise at least one of: PotassiumBromide (“KBr”), Calcium Fluoride (“CaF₂”), and a material having a CTEof at least one of: about 5 ppm/degree C.-about 10 ppm/degree C., about10 ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C.;and each include bonding material on at least a periphery thereof; (iii)the three pins of the compensator securing apparatus at least one of:each comprise at least one of: Potassium Bromide (“KBr”), CalciumFluoride (“CaF₂”), and a material having a CTE of at least one of: about5 ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degree C.-30ppm/degree C., and greater than 30 ppm/degree C.; and each includebonding material on at least a periphery thereof; (iv) the framecomprises at least one of Zinc, Aluminum, Magnesium, an Aluminum-Zinc ora Zinc-Aluminum alloy; (v) the frame includes one or more recessesdisposed on a surface of at least one of the first plate and the secondplate, the one or more recesses operating to dissipate heat; (vi) atleast one of the beamsplitter, the beamsplitter securing apparatus, thethree pins of the beamsplitter securing apparatus, the compensator, thecompensator securing apparatus and the three pins of the compensatorsecuring apparatus comprise a first material; and at least one of thefirst plate and the second plate of the frame comprise a secondmaterial; the first and second materials having one or more coefficientsof thermal expansion that are at least one of identical, substantiallythe same, and as close as practicable to each other; (vii) when thefirst and second materials have one or more coefficients of thermalexpansion that are as close as practicable to each other and when thefirst material comprises at least one of: Potassium Bromide (“KBr”),Calcium Fluoride (“CaF₂”), and a material having a CTE of at least oneof: about 5 ppm/degree C.-about 10 ppm/degree C., about 10 ppm/degreeC.-30 ppm/degree C., and greater than 30 ppm/degree C., the secondmaterial comprises at least one of: Zinc, Aluminum, Magnesium, anAluminum-Zinc or a Zinc-Aluminum alloy, and a material having a CTE ofat least one of: about 23 ppm/degree Celsius, higher than 23 ppm/degreeCelsius, about 23.4 to about 23.6 ppm/degree Celsius, about 23 to about27 ppm/degree Celsius, and about 23 to about 28 ppm/degree Celsius; and(viii) at least one of the beamsplitter and the compensator and at leastone of the first plate and the second plate of the frame comprisematerials having different coefficients of thermal expansion.
 14. Theinterferometer of claim 10, further comprising one or more recessesdisposed on a surface of at least one of the first plate and the secondplate, the one or more recesses operating to dissipate heat.
 15. Amethod of mounting one or more components of an optical instrument,comprising the steps of: disposing an optical element having a firstsurface, a second surface, a third surface, a fourth surface, at least afirst landing point or area on or against the third surface of theoptical element, at least a second landing point or area on or againstthe fourth surface of the optical element, and at least a third landingpoint or area on or against the fourth surface of the optical element inbetween a first plate and a second plate of a frame such that theoptical element extends between the first plate and the second plate,the third surface of the optical element extending between the first andsecond surfaces of the optical element and operating to be disposedagainst or adjacent to the first plate of the frame and the fourthsurface of the optical element extending between the first and secondsurfaces of the optical element and operating to be disposed against oradjacent to the second plate of the frame; and mounting the opticalelement to the frame using an optical element securing apparatuscomprising three pins each having a first end and a second end such thatthe optical element has limited or no exposure to at least one ofbending, warping, tilting and distorting, wherein: (i) the at leastfirst landing point or area of the optical element operates to receiveat least a first pin of the three pins of the optical element securingapparatus thereon or thereagainst and to align with a respective firsthole of the first plate such that the at least first pin of the threepins of the optical element securing apparatus operates to also bedisposed in the first hole of the first plate, thereby forming anattachment between the optical element and the first plate; (ii) the atleast second landing point or area of the optical element operates toreceive at least a second pin of the three pins of the optical elementsecuring apparatus thereon or thereagainst and to align with arespective first hole of the second plate such that the at least secondpin of the three pins of the optical element securing apparatus operatesto also be disposed in the first hole of the second plate, therebyforming an attachment between the optical element and the second plate;and (iii) the at least third landing point or area of the opticalelement operates to receive at least a third pin of the three pins ofthe optical element securing apparatus thereon or thereagainst and toalign with a respective second hole of the second plate such that the atleast third pin of the three pins of the optical element securingapparatus operates to also be disposed in the second hole of the secondplate, thereby forming an attachment between the optical element and thesecond plate.
 16. The method of claim 15, further comprising: disposingthe first end of at least a first pin of the three pins of the opticalelement securing apparatus on or against the at least first landingpoint or area of the optical element; disposing the second end of the atleast first pin into a respective first hole of the first plate suchthat the at least first pin of the three pins of the optical elementsecuring apparatus operates to be disposed on or against the at leastfirst landing point or area of the optical element and in the first holeof the first plate, thereby forming an attachment between the opticalelement and the first plate; disposing the first end of at least asecond pin of the three pins of the optical element securing apparatuson or against the at least second landing point or area of the opticalelement; disposing the second end of the at least second pin into arespective first hole of the second plate such that the at least secondpin of the three pins of the optical element securing apparatus operatesto be disposed on or against the at least second landing point or areaof the optical element and in the first hole of the second plate,thereby forming an attachment between the optical element and the secondplate; disposing the first end of at least a third pin of the three pinsof the optical element securing apparatus on or against the at leastthird landing point or area of the optical element; and disposing thesecond end of the at least third pin into a respective second hole ofthe second plate such that the at least third pin of the three pins ofthe optical element securing apparatus operates to be disposed on oragainst the at least third hole of the optical element and in the secondhole of the second plate, thereby forming an attachment between theoptical element and the second plate.
 17. The method of claim 16,wherein at least one of: (i) at least one of the at least first landingpoint or area of the optical element, the at least second landing pointor area of the optical element and the at least third landing point orarea of the optical element is at least one of: coplanar, coplanar withthe third surface of the optical element, not coplanar, not coplanarwith the third surface of the optical element, coplanar with the fourthsurface of the optical element, not coplanar with the fourth surface ofthe optical element, coplanar with one or more surfaces of the opticalelement, not coplanar with one or more surfaces of the optical element,substantially parallel with the third surface of the optical element,substantially parallel with the fourth surface of the optical element,and substantially parallel with one or more surfaces of the opticalelement; (ii) the three pins of the optical element securing apparatusare sized and shaped to fit within their respective holes of the firstand/or second plates of the frame and to be disposed on or against, andwhose ends contact, their respective landing points or areas of theoptical element such that the optical element is in substantial contactwith, and/or is disposed substantially adjacent to, the first and secondplates of the frame; (iii) the three pins of the optical elementsecuring apparatus each include bonding material on at least a peripherythereof, the bonding material operating to bond the three pins of theoptical element securing apparatus to the optical element and at leastone of the first plate and the second plate of the frame; (iv) the threepins of the optical element securing apparatus and the optical elementcomprise the same material(s); (v) the optical element and at least oneof the first plate and the second plate of the frame comprise materialshaving different coefficients of thermal expansion; (vi) the frameincludes one or more recesses disposed on a surface of at least one ofthe first plate and the second plate, the one or more recesses operatingto dissipate heat; (vii) at least one of the optical element, theoptical element securing apparatus and the three pins of the opticalelement securing apparatus comprises at least one of: Potassium Bromide(“KBr”), Calcium Fluoride (“CaF₂”), and a material having a CTE of atleast one of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C.;(viii) the frame comprises at least one of Zinc, Aluminum, Magnesium, anAluminum-Zinc or a Zinc-Aluminum alloy; (ix) at least one of the opticalelement, the optical element securing apparatus and the three pins ofthe optical element securing apparatus comprise a first material; and atleast one of the first plate and the second plate of the frame comprisea second material; the first and second materials having one or morecoefficients of thermal expansion that are at least one of identical,substantially the same, and as close as practicable to each other; (x)when the first and second materials have one or more coefficients ofthermal expansion that are as close as practicable to each other andwhen the first material comprises at least one of: Potassium Bromide(“KBr”), Calcium Fluoride (“CaF₂”), and a material having a CTE of atleast one of: about 5 ppm/degree C.-about 10 ppm/degree C., about 10ppm/degree C.-30 ppm/degree C., and greater than 30 ppm/degree C., thesecond material comprises at least one of: Zinc, Aluminum, Magnesium, anAluminum-Zinc or a Zinc-Aluminum alloy, and a material having a CTE ofat least one of: about 23 ppm/degree Celsius, higher than 23 ppm/degreeCelsius, about 23.4 to about 23.6 ppm/degree Celsius, about 23 to about27 ppm/degree Celsius, and about 23 to about 28 ppm/degree Celsius; and(xi) the optical element comprises at least one of a beamsplitter and acompensator.
 18. The method of claim 17, further comprising at least oneof: bonding a first support member between a first portion of the firstplate and a first portion of the second plate and/or bonding a secondsupport member between a second portion of the first plate and a secondportion of the second plate; disposing a first support member between afirst portion of the first plate and a first portion of the second plateand disposing a second support member between a second portion of thefirst plate and a second portion of the second plate, the first andsecond support members being integrally formed with the first plate andthe second plate, thereby forming a single part, wherein the firstsupport member and the second support member each comprise at least oneof the same material or materials having one or more coefficients ofthermal expansion that are at least one of: identical, substantially thesame, and as close as practicable to each other; and attaching a mirrorto the frame such that the mirror has a reflecting surface in areflecting relation with the optical element, wherein the opticalassembly is substantially stable regarding the reflective relationshipbetween the mirror and the optical element.
 19. The method of claim 18,further comprising at least one of: (i) attaching a second mirror to theframe such that the second mirror has a reflecting surface facing awayfrom an interior space of the frame, and the second mirror is inreflecting relation to the optical element through a retroreflector,wherein at least one of: (i) the frame includes at least another holethat operates to receive at least one additional pin therein; (ii) themirror and the second mirror each include at least one landing point orarea that operates to receive the at least one additional pin thereon orthereagainst, thereby creating respective attachments between the frameand the mirror and the second mirror when the at least one additionalpin is disposed in the at least another hole of the frame and isdisposed on or against the at least one landing point or area of themirror and/or the at least one landing point or area of the secondmirror; (iii) the at least one additional pin comprises the samematerial as the material used for at least one of the frame, the mirrorand the second mirror; and (iv) the mirror and the second mirror aremade of at least one of: the same material as each other, the samematerial as the frame and the same material as the frame and each other;(ii) disposing a protruding member on the frame such that the protrudingmember has a first portion extending from a surface of either the firstplate or the second plate of the frame, a second portion, and a groovedefining the first and second portions of the protruding member on eachside of the groove, the groove of the protruding member beingconstructed to dissipate and/or eliminate one or more stresses passingthrough the protruding member, thereby preventing the one or morestresses from affecting the optical assembly; (iii) aligning one or moreof the first plate, the second plate, the first support member, thesecond support member, the mirror, the second mirror, the opticalelement, and the three pins of the optical element securing apparatusbefore locking the alignment in place with at least one of friction,fusing, bonding and adhering; and (iv) when the material or materials ofthe first support member and the material or materials of the secondsupport member have one or more coefficients of thermal expansion thatare as close as practicable to each other and when the material ormaterials of one of the first and second support members comprise atleast one of: Potassium Bromide (“KBr”), Calcium Fluoride (“CaF₂”), anda material having a CTE of at least one of: about 5 ppm/degree C.-about10 ppm/degree C., about 10 ppm/degree C.-30 ppm/degree C., and greaterthan 30 ppm/degree C., the material or materials of the other of thefirst and second support members comprise at least one of: Zinc,Aluminum, Magnesium, an Aluminum-Zinc or a Zinc-Aluminum alloy, and amaterial having a CTE of at least one of: about 23 ppm/degree Celsius,higher than 23 ppm/degree Celsius, about 23.4 to about 23.6 ppm/degreeCelsius, about 23 to about 27 ppm/degree Celsius, and about 23 to about28 ppm/degree Celsius.
 20. The method of claim 19, wherein at least oneof: (i) at least one of the first and said second portions of saidprotruding member is at least one of: having a substantially circularshape and being of any geometric shape; (ii) the first portion of theprotruding member is smaller than the second portion of the protrudingmember; (iii) the first portion of the protruding member has a surfacethat is in contact with either the first plate or the second plate ofthe frame and the surface of the first portion of the protruding memberhas at least one of: a smaller diameter than a lateral cross-sectionand/or a bottom surface of the second portion of the protruding memberthat is disposed in an opening of a mount that operates to secure theoptical assembly in place; and a smaller surface area than a lateralcross-section and/or a bottom surface of the second portion that isdisposed in the opening of the mount that operates to secure the opticalassembly in place; (iv) the first portion of the protruding member has asmaller volume than the second portion of the protruding member; (v) thegroove is at least one of: a space between the frame and at least one ofthe second portion of the protruding member and the mount such that theframe is spaced away from the at least one of the second portion of theprotruding member and the mount; and operating to achieve and/ormaintain at least one of: dimensional stability, a predetermined degreeof flatness and a high degree of flatness of at least one of: aboutλ/10, about λ/15, about λ/20, about λ/30, between about λ/10 and aboutλ/15, between about λ/10 and about λ/20, between about λ/10 and aboutλ/30, between about λ/15 and about λ/20, between about λ/15 and aboutλ/30 and between about λ/20 and about λ/30; (vi) the protruding memberis at least one of integrally formed with the surface of the first plateor the second plate; and bonded to the surface of the first plate or thesecond plate, the bonding being at least one of fusing and adhering;(vii) the groove of the protruding member extends along and/or incommunication with a perimeter of the first portion of the protrudingmember and is at least one of: having a substantially circular shape;and being of any geometric shape; (viii) the groove of the protrudingmember includes at least one of: one or more right angles, one or moreslopes, one or more chamfered surfaces having a consistent slope, one ormore chamfered surfaces having a changing convex slope, one or morechamfered surfaces having a changing concave slope, and one or moretapers; (ix) the groove is formed at substantially a right angle suchthat a first portion of an outer surface of the protruding memberextends from the second portion of the protruding member inwardlysubstantially parallel to the surface of the first portion of theprotruding member and a second portion of the outer surface of theprotruding member extends from the first portion of the outer surfacevertically substantially at a right angle and/or perpendicular to thesurface of the first portion of the protruding member; and (x) the oneor more stresses comprises at least one of: connection and/or clampingstress resulting from clamping the protruding member to the mount,stress passing through the mount, stress passing through the protrudingmember, sheer stress, rotational stress and stress resulting from one ormore changes in temperature.
 21. The method of claim 15, furthercomprising disposing one or more recesses on a surface of at least oneof the first plate and the second plate, the one or more recessesoperating to dissipate heat.